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1. ni E TTL 1 E p EL Ji Jou E i A I I DESCRAMBLER PARTS We stock the exact parts PC board and AC adaptor for Radio Electronics February 1984 article on building your own Cable TV Descrambler 701 PARTS PACKAGE 29 95 Includes all the original resistors capacitors diodes transistors integrated circuits coils IF transformers toko BKAN K5552AXX Original 14 volts DC 285ma ac adaptor used in the article S P E CT ALS BOTH 4701 amp 3702 esl Now 39 ALL THREE 701 4702 amp 704 now 49 e 9 eeoesetevneeweeetreeeeeetgetee 9 9 9 9 ee eevee FREE Reprint of Radio Electronics article February 1984 on Building Your Own CABLE TV DESCRAMBLER with any purchase of above AC ADAPTOR ORDER TOLL FREE OVDC SOOMA aa amia a rem 55 95 1 800 22 8529 inside MA 617 339 5372 PROMS 4k x 8 e VISA MASTERCARD OR C O D P2T3S2SATq2TV veva a5 e rag d 3 5 Call or write for a free catalog ADD 2 50 SHIPPING AND HANDLING 4 50 FOR CANADIAN ORDERS J e W WE ALSO OFFER QUANTITY DISCOUNTS ON S OR MORE UNITS ELECTRONICS ICC o eoo mia P O BOX 800R MANSFIELD MA 02048 CIRCLE 708 ON FREE INFORMATION CARD The best DMM inits class just got better The Fluke 80TK One innovation leads to another First there was the 70 Series which set a new standard for low cost high performance Fluke quality multimeters An
2. Stand by batteries EM Two 9V alkaline batteries wired in parallel are recommended Key Switch Mount on or near front door Switches alarm on and off iN SS N pf i 3 5mm adaptor socket m Accepts plug from mains f Ad P adaptor 9V type if 9V batteries are used A Fire Bell The simplest type of alarm device If polarised connect in manner shown Siren module may be used instead of fire bell lt I eq Reed Switch amp Magnet Mount reed switch on frame magnet on window so they align with each other when window is closed Normally closed loop Pressure Mat Place under carpet or rug in doorway etc where intruder is likely to walk Any number of additional sensors may be b Normally open loop connected N C types in series N O types in parallel Fig 3 When connecting the controls power ringer and sensor follow this outline The pressure mat is connected to the board at the position in the schematic diagram that s shown with paralleled Switches 5 to 7 minutes and then deactivate if the circuit is working correctly Applications First of all you must decide what use home or auto your Alarm will be put to Different connections are required for each purpose For a Home Alarm system the next step is to place the Alarm circuit in a protective case In a normal Home Alarm installation the Alarm works are nor mally hidden away for security in a cup board or cl
3. Special Projects 7 8 9 NOT AVAILABLE C Special Projects 10 Spring 84 4 50 C Radio Electronics Annual 1983 3 50 C Radio Electronics Annual 1984 3 50 C Radio Electronics Annual 1985 3 50 Radio Electronics Annual 1986 2 50 How to Make PC Boards 2 00 SA ADOUT KIIS c e e 2 00 Modern Electrics Vol 1 31 2 25 April 1908 Electro Importing Co Catalog 4 95 1918 176 pp Low Frequency Receiving Techniques Building and using VLF Antennas New ideas 42 circuits for exoerimenters 3 50 T Descrambler Jan Feb 1981 3 00 C Descrambling Feb 1984 2 00 C Receiving Satellite Television 7 00 If you need a copy of an article that is in an issue we indicate is unavailable you can order it directly from us We charge 506 per page Indicate the issue month amp year pages and article desired Include payment in full ptus shipping and handling charge currently 9 550 kHz and 15 140 KHz Its daily schedule runs from 0930 until 0330 GMT UTC and it has been heard recently in Spanish about 0100 GMT UTC with decent signals Another Chilean shortwave station 15 Radio Mineria which transmits on 9 750 kHz There are a number of Peruvian outlets on SW There seem to be more new sta tions on the air from Peru lately than from any other Latin American country Many of
4. operators 1 800 426 2200 manual two 10X probes 15 day return policy and worldwide ser vice backup Order toll free 1 800 426 2200 Ask for Rick In Oregon call collect 503 627 9000 Or write Tektronix Inc P O Box 1700 Beaverton OR 97075 Tektronix COMMITTED TO EXCELLENCE Copyright 1985 Tektronix Inc All rights reserved TTA 439 3 t Price F O B Beaverton OR 3 year warranty includes CRT CIRCLE 718 ON FREE INFORMATION CARD Volume 3 No 1 January February 1986 SPECIAL PROJECT BUILDERS 16 PAGE SECTION Budget Project Parade 53 Multi purpose Flashing LED 56 Electronic Dice 59 A Simple Amplifier 62 Home and Car Alarm 65 Integrated Shortwave Receiver 67 Electronic Siren FEATURES Identifying Unknown IC s let the chips signature detect its function and type SWR what it means in practice Assemble a Computer Monitor from a Kit we check out the Heathkit HVM 122A 12 inch monitor Digital Fundamentals Understanding counters and shift registers Inside Oscilloscopes Application rules you should know yes Before and aft PROJECTS YOU CAN BUILD Digital Cribbage Board modern day computer scoring for an old card game Before and After Clock see the time as you tell it Adjustable Timer the beginning of many new projects Telephone Remote Control System let the touch tone signals trip in house switches Quicky Telephone Tester are your lines polarized corr
5. you name it And as high technology grows electronics will grow Which means few other fields if any offer more career opportunities more job security more room for ad vancement if you have the right skills SPECIALISTS NEED SPECIALIZED TRAINING It stands to reason that you learn anything best from a specialist and CIE is the largest independent home study school specializing exclusively in electronics with a record that speaks for itself According to a recent survey 9296 of CIE graduates are employed in electronics or a closely related field When you re investing your time and money you deserve results like that WITH CIE THE WORLD OF ELECTRONICS CAN BE YOUR WORLD TOO START WHERE YOU WANT GO AS FAR AS YOU WANT CIE s broad range of entry intermediate and advanced level courses in a variety of career areas gives you many options Start with the Career Course that best suits your talents and interests and go as far as you want all the way if you wish to your Associate in Applied Science Degree in Elec tronics Engineering Technology But wherever you start the time to start is now Simply use the coupon below to send for your FREE CIE catalog and LOEBENDENIISTUDY complete package of career information ATTENTION Or phone us at 1 800 321 2155 in Ohio 1 800 362 2105 Don t wait ask for your free catalog now After all there s a whole world of electronics out the
6. Electronics Paperback Books ELECTRONIC SE CURITY DEVICES _ WRITE ZX SPEC TRUM GAMES PRO INTO THE QL AR INTRODUCTION TO GRAMS Reg Price CHIVE Reg Price ART OF PROGRAM Ww ELECTRONIC VIDEO Reg Price Reg Price Sram NOW PTE NOW ONLY wee NOW ONLY 5 00 MING THE 2X SPEC 20 PROGRAMS FOR ELECTRONIC PROJ HOUSEHOLD PROJ NOW ONLY ONLY 4 00 Three basic 5 00 Step by step How you can use this TRUM Reg Price ZX SPECTRUM amp 16K ECTS USING SOLAR ECTS Reg Price 4 00 For the person sections Switch acti guide shows how to write database program sup wee NOW ONLY ZX81 Reg Price LINEAR IC EQUIV CELLS Reg Price NOW ONLY who has just or is about vated alarms intra red amp 3 75 Includes 2 tone Door Buzzer Auto Porch Light Lamp Oimmer anc Sees NOW ONLY 4 00 Simpie circuits powered by the energy of ALENTS AND PIN CONNECTIONS 12 50 shipping free 6 25 Using BASIC to make your Spectrum do clever things Sees NOW ONLY 4 00 Programs with fiow charts Card games phed with the Sinclair QL to buy a video recorder ultrasonic systems smoke gas water detec tion graphics games Lum m oum um um um um um um eee Gm m m Gm Bm S m UU GR UR m m Um COMMODORE 64 5 00 Masses of useful info and programming tips not found in any users Manual MICRO INTERFAC ING CIRCUITS BOOK ever 5 00 Practical add ons transform your computer
7. 59 i s y i 35 53 00 577 5 2w 4700 45 25 2235 14588 4 a 1 hi 1 eye A f de s at Resietor ss0rtrne Standard a licia ir t dcl ad T Sa 735 53 Ml 577 Su AS102 5 ach of vel 047 nt 0 47 E 1B 154 1283 13 108 B 354 Fisiemirle oc ie agio X E M E 4B gt ENEBO 8N 790 a 3 63 00 577 50 values Q 10 69 929 96 5 19 15 1283 19 108 894 i r maa heh n NESOZON 1 96 ANI ede DANS Ca ie Fagg Mas 75 700 5000 Ow 256 total pcs 50 wocb us n 109 aw Mime Raestance 126 C 1000MO F bi N SOSAFE 563 TIPS 7 700 000 550 0v R5202 5 each of veiues 820 0 7 5k 2 1 1 1283 13 08 894 altaga Coefficient OC Nagiba pate be NESOSEN 2 86 NEC Mem Chi IP62 75 700 OO 55000 1255 total pes l i m De Mpa slm pgs JALS32N 45 NESO37N 86 ory ips 85302 5 10 2 2 rE Is ay he 18 378 Electrodes Matslired him pach of values 242 to 2 0 5 DS 1 135 1120 ee ett 9 NESAION 13 751 Digl Key 1 AMP SILICON RECTIFIERS 1255 total pes dili us bad 2 fa 22 18 3519 teed Spacing 200 300 JALSAON E 3134 Pert No Dsscriprin Price 2 50 32 269 2743 23 1 157 Seif Healng Yes er MA NESSDN 24 parsa 20 Dynamic RAM ws iras 1 100 205 1 100 5 Wirewound Rec Resistors LE OM IA BS Som Ung wee V SERIES asad TA NESEMN 1 809 baisi6c 20 Dynamic RAM Dp 39 i Pe ee ETY Mb 2 5 Im MM MOX SY E Ey a aiios SLS47N ee D41254C 20 Dynami RAM 18 Di 16 43 220 BWI 330 50 76 850 5414 a 7ALS4BN 13 NES53AN 128 D21 7AD 2 Stave RAM BOD sel sonny oO le sm 84
8. SINGLE IC PROJ ECTS 4 285 A projects in this book are based on one C and are Simple to construct Great way to gel started with IC s ELECTRONIC SYN THESIZER PROJECTS ates 4 50 How to as semble the elements of a synthesizer and then put them al together CHECK OFF THE BOOKS YOU WANT more ELECTRONIC GAMES Reg Shel NOW 3 50 BUILD SW RADIO RCVRS Reg 3an NOW 4 00 50 LED CIRCUITS Bk 2 Reg Ji 96 NOW 3 25 INTRO TO 6502 MACHINE CODE Reg Dett NOW 4 00 LOG 4 94 An up to date directory of AM FM and TV stations includ ng a section On worid wide shortwave stations INTERNATIONAL TRANSISTOR EQUIV ALENTS 7 50 Locates possibie sub stitutes for a popular user onented selection of modern transistors Japa nese European and American lypes KEtestronkt Popular Plage nit ynthesisor Electronic Projects Circuds POPULAR ELEC TRONIC PROJECTS 4 75 A collection of a wide range ol electronic Projects and circuits for the expermenter Number of books ordered Srereta cf the An totroductian Computer 25 Shople COMMODORE 64 to Programming Terminology w Arateur Bard i Amean Bi the ATARI Explainest Aer ots ipiam 500 BEN KL requency i i 1 EE bs Eo ANNES La H i J DM E 1 SECRETS OF THE INTRO TO PRO COMPUTER TECH INTRO TO 2 80 MA ANTENNA PROJ WHITE S RADIO CONFIDENTIAL INTRODUCTION TO FREQUENCY LIST 6
9. 2 2K 05 O R1 1 2 L 100K U6 a c U6 b Z e n R83 02 1 6 CD4584 U6 f Ze 22e 1 6 CD4584 inter ONEA gamo eh The counter circuit that s made up of U2 and the decoder driver chips UI and U3 constitute the two digit PLAY counter Pushbutton switch S2 clears the play counter before entering each new play count The counter circuit comprised of U8 along with decoder drivers U7 and U9 and flip flop U4 make up the three digit total point counter The flip flop was used instead of another counter to indicate one hundred The output of U4 is coupled to QI which acts as a driver for the Fig 2 Foil pattern for the Digital Cribbage Board s printed circuit is shown full scale Note that if the pattern were cut down the center you d have two identical circuit board patterns two segments used to indicate the number 1 on DIS3 Pushbutton switch S3 clears counter U8 and resets flip flop U4 to start a new game The inverting Schmitt triggers U6 a and U6 b make up a Squarewave generator with a 50 duty cycle The output of that generator is coupled through U6 e to the blanking inputs of Ul and U3 The generator output is also fed to the blanking inputs of U7 and U9 through U6 f That squarewave signal PARTS LIST FOR DIGITAL CRIBBAGE BOARD SEMICONDUCTORS DIS1 DIS5 HP 5082 7653 7 segment common cathode display Jameco Electronics Qi 2N3903 NPN silicon bipolar transistor _ Ui U3 U7 U9 CD4511
10. 308650 R420 6 ND 58 5250 32959 295350 A420 18 NI 668 5907 38458 33105 RA20 36 NF 78 5093 342855 3836 A221 5D 659 6180 38632 346 00 R421 18 ND PHB 6955 13335 388000 R421 36 NO 9 8114 51292 451000 R427 8 ND 7064 44120 3950 0D R422 18 NI B050 SpQ00 117500 943 e S 5499 445 L nn RREL RRB EERE 168 40 1NS65B couv 185 5C 86 30 21 80 amp 1716 00 1914 06 1439 00 1518 Of 3617 06 1716 00 1914 De 1415 00 151g DO 16817 00 1716 06 1914 00 1221 00 1347 00 1473 06 Part No 1599 90 N4728A 1851 DO 16 1221 00 184750A 1347 00 1473 00 1599 00 161 00 2216 00 2342 00 2468 00 16 VN9 BB ias 90638 eque NB HIE equiv 1 R REEZEE R EPELE t v 1887 18 rau Oo 00 CO DD C Ch Oh c c Oi ope ode Dor 26 09 zz zzzzz 23 73 33 38 puanson BB 288 zzzzzz5 PEXszocHOHBBEHERSSRS D Submintature Connectors Vonage 1 33V 25 483 amp 305 ab 342 08 333 79 363 86 a8 74 49795 347 98 14 90 36 76 5456 5311 58 tis 67 65 J8 185 x060 D d D 38 X062 x063 Sokder Pot Digi Key No of Part Na Pina 159P Ny 9 1595S Nia 8 TSI1SP NO 15 1814S ND 16 1 26P MD 25 18255 ND 25 1537P sib 37 1537S Mp 37 1S59P NO EU 1550S RO 50 HOS NL 9 Pin Hood H015 NJ 15 Pi Hood HD25 ND 25 Pin Hood HD37 ND 37 Pin Hood HDI N 50 Pin Hood Streigi PCB Mount 1159P amp D 3 1tS9S 5 0 9 1514P ND 15 115158 ND K 11825P D 5 115255 AD 1837P ND Mate 118375 D 3 Female Right Angi
11. 706 AP Products n LE CIE n IMEEM 19 21 C O M B l l NEER 710 Datak West TOIT E 716 717 Dick Smith E E E E Diehl Engineering OE SE 705 Digi kev fau woe SIN Electronic Book C jub P ENS E Electronic Technology Today EM 707 Fluke Vente beet aie t 719 Hester eae ee ee EI 20 712 Information Unlimited vm 708 J amp W Electronics Inc CV3 713 Keypro Circuit Systems Tan 714 Mouser CR NRI F Peres Ss 715 Oregon Microwave E 108 Pacifice Cable sero Vs 17 RE Bookstore T zc MORE 718 Tektronix CV2 Continued from page 104 Venuzuela station Radio Rumbos which can be heard without difficulty on 9 660 kHz Throughout the evening hours from 0000 to 0600 GMT UTC you can find English programs from Radio Havana Cuba Frequencies are 6 090 6 100 and 9 745 kHz Those who appreciate the Cuban rhythms will enjoy the show called From the Land of Music at 0435 hours Mexico has a number of different short wave outlets in operation XEWW La Voz de America Latina The Voice of Latin American can be heard in Spanish throughout the evening on 6 165 and 9 515 kHz The Mexican government operates its own station XERMX Radio Mexico In ternational with some occasional En glish segments on 9 705 and 15 430 kHz The daily schedule runs from 2000 to 0500 hours GMT UTC Skimming the bands for other Latin American signals we find Guatemala Radio
12. Amplitiers of all kinds to add to the cir cuits trom Book 1 of this series PRACTICAL ELEC TRONICS CALCULATIONS AND FORMULAE 7 50 A workShop manual that bridges the gap between complicated tech theory and cut and try _ POPULAR ELEC TRONIC CIRCUITS Book 1 5 00 Mo e circuits for hobbyists Au dio radio test music household and more POPULAR ELEC TRONIC CIRCUITS Book 2 5 75 More useful Circuits None o these projects duplicate those in Book 1 of this senes HO1 86 x t Your guide to every SS thing that s new in elec SS tronics computers and technical education Over 400 items Discover fascinating kits to build enjoy and learn with as well as assembled high tech products for home business and hobby Get our famous High Tech Ca j e S CE Heath Company Dept 107 374 i Benton Harbor Michigan 49022 i MAIL COUPON TODAY and receive the latest issue of the Heathkit Catalog free of charge Name Heathkit maisa bs ci State E Heath Fam i Company i CL 783BR1 Zip 1 A subsidiary of Zenith Electronics Corporation kaum uu emen anas snam unam suum unas uae GY m ce um um s um um us us al CIRCLE 719 ON FREE INFORMATION CARD HANDS ON ELECTRONICS N Every IC has its own signature or DIF ature A logical exploration of characteristics will uncover the chip s function and help you give it a proper name JONE OF
13. Fluke Holland B V PO Box 2268 5600 CG Eindhoven The Netherlands 040 458045 TLX 518 Copyright 1985 John Fluke Mtg Co Inc All rights reserved Ad No 4709 70 80 CIRCLE 707 ON FREE INFORMATION CARD
14. For every eight clock pulses that occur the 5 bit word counter or address counter is incremented to up date the address E SHORT QUIZ ON DIGITAL FUNDAMENTALS LESSON 5 COUNTERS AND SHIFT REGISTERS 1 A four bit binary up counter is preset to 0010 Seven input pulses occur The decimal value of the counter content is a 2 c 9 b 7 d 11 2 The maximum number of states that a 6 bit counter can r present is ai Lais TP 3 The maximum number count capability ola a 7 bit counter is 4 A three bit binary counter is cascaded with a BCD counter An input frequency of 400 kHz is applied to the circuit The output frequency is kHz 5 How many BCD counters does it take to represent the number 18900 a 2 c 4 b 3 d 5 6 A four bit binary down counter is preset to 0011 Six input pulses occur The binary value of the couriter con tent is a 0011 c 1010 b 0110 d 1101 7 Clearing a counter or shift register means the same as presetting it to 8 The maximum count of a four bit BCD counter is a 1000 c 1010 b 1001 d 1111 9 Counters and shift registers are a type of logic circuits 10 List four ways that data can be entered stored and read out of a shift register Od lcm M nC b ONERE RON Pat ter oes ae Concluded on page 108 SERIAL QUT 986 8a3d NVTC e o HANDS ON ELECTRONICS e o Friedman on Computers Continued from page 104 the minimum practical value in ter
15. Insert the plug of the Control System s AC power cord into a 117 volt AC outlet 8 Re connect the in house wiring to the telephone company s wiring at the protected interface Single Multiple Telephone Checkout l For the single phone installation take the telephone connected to the Control System off hook and listen for a dial tone For a multiple installation any telephone can be taken off hook 2 Make a call to verify that the jacks are working properly then hang up the telephone 3 Lift the telephone off hook wait l second then dial your access code followed by the digit 9 Remember that the access code is a two digit number the first of which is always dua n 4 Verify that the light s connected to the wall switch REMOTE CONTROL SYSTEM C6 C7 C11 01 F ceramic disc C8 6 8 to 10 pF ceramic disc C9 18 pF ceramic disc C10 4 7 pF 6 WVDC electrolytic ADDITIONAL PARTS AND MATERIALS K1 5 volt relay SPDT Aromat P N DS1 M DC5V or similar S1 S7 7 SPST switches in a DIP package printed circuit mount T1 Transformer 117 VAC primary winding 12 6 volts center tapped 350 ma secondary winding EDW P N EL 12 350A6 or similar T2 Pulse transformer Sprague 1122100 Y1 6 00 MHz crystal Miscellaneous AC line cord modular phone extension cords printed circuit board plastic case with plastic cover mounting hardware wire solder etc The following are available from Master Contr
16. La Jolla CA 92038 Tel 800 368 5719 in California 800 643 8382 Lap Computer The portable ZP 150 lap computer a diskless unit from Heath is being offered as a fully assembled computer product It weighs only 7 7 pounds and has an LCD Liquid Crystal Display screen built into its flip top It is the first lap computer to use Microsoft WORKS a ROM based software package developed by Microsoft Corporation which is compatible with MS DOS machines The ZP 150 has 224 kilobytes of ROM and 32 kilobytes RAM ELD JOUR OW ative lon Generators and CAN BU LD is jst vou In dete nct ded a sta Yo ass tor ia suitable ch rating Meach i tot begin hobbyists x suitable tor venced as tot A ng techia ath soos igeri n Il gt i JS 345 ye Eu t Ta user memory which is expandable to 416 kilobytes Built into WORKS are several business programs including PLAN a subset of Microsott s Multiplan WORD a subset of the powerful word processor WORD by Microsoft FILE a recently developed Data Base Management System DBMS CALENDAR an appointment secretary TELCOM a telecommunications pro gram complete with auto dialing ca pability and BASIC a large subset of the popular programming language GW BASIC In addition to the ROM based business software the ZP 150 has a paral lel printer port an RS 232 serial port an
17. Note that the decimal number of input pulses applied to the counter corresponds to the binary value displayed by the outputs That is true only if the counter has been reset prior to counting An important point to note is that when fifteen input pulses have occurred the binary number stored is 1111 When the l6th input pulse occurs flip flop A toggles to 0 that in turn toggles B to 0 which in turn toggles C to 0 and in turn toggles D to 0 The binary number indicated in the counter at that time is 0000 That is equivalent to the initial reset state described earlier In other words the number 16 is too large PULSES TO BE COUNTED 1 2 3 4 5 6 7 8 g 10 11 12 13 1 15 16 Fig 3 input and output waveforms for a 4 bit binary counter RECYCLE for the counter which cannot store it Once that 4 bit counter counts to 15 the next input pulse simply recycles it back to zero and it starts again Figure 3 shows the input and output waveforms for the 4 bit binary counter as 16 input pulses are applied Those timing waveforms illustrate all possible states of the counter You may want to trace through the logic diagram of the counter and correlate each of the pulses shown in the timing diagram with each flip flop That will ensure that you understand how each flip flop changes state on the high to low transition of the next input pulse Counting to Higher Values To count to larger numbers all you have to do 1s add more flip flops
18. Therefore the sync identifier takes 4 AC cycles or approximately 32 milliseconds In contrast to the sync identifier all remaining bit patterns are transmitted in their true form during the first AC cycle then it s compliment form during the next 4 AC cycle after zero cross is detected As an example if you were to transmit house code A the format would be as shown in Fig 4 The processor circuitry shown in Fig 2 consists of single component microprocessor Ul erasable programmable read only memory chip or EPROM U3 and an address latch U2 The microprocessor U1 is a 40 pin package that contains an 8 bit CPU 64 bytes of RAM of which 32 bytes are actually user available 27 I O lines and an 8 bit timer event counter All instructions are either one or two bytes long and can be executed in one or two cycles Thus using a 6 MHz crystal TABLE 3 HOUSE CODES 9861 H3J4 NVFP N HANDS ON ELECTRONICS J NO CLK 5V 40 C11 01 20 E C10 Fe OTT 4 ISOLATOR 5V D1 1N4148 PHONE LINE OUTPUT ihk i Es 5182 510 instructions can be carried out in 2 5 microseconds or 5 0 microseconds respectively Of the 27 I O lines available DB7 DBO are dedicated as a data bus providing information from the program memory Port reads the 7 bit switch to determine the house code and access code programmed in the unit Port 2 lower bits contain the upper address bits of t
19. any small box or chassis may be used Regardless of the type of box that you choose it should have some form of front panel on which to mount the time selection dial potentiometer R1 the two pushbutton switches and the status lamps If such construction is decided on a small toggle or slide switch should also be used to disconnect the battery when not in use By the way even though a 6 volt battery is suggested there is little reason why a 9 volt unit cannot be substituted as the frequency of oscillation timing is almost entirely independent of battery potential You may however want to check to make sure that the light emitting diodes are not passing too much current When mounting the time adjustment potentiometer RI a pointer type knob should be affixed to the shaft A stopwatch or other timer may be used to check the time at each individu al position the control will represent Mark major portions such as second 10 seconds etc until you have enough markings to be able to make use of the timer for the intended application In general the better the quality of the capacitor used for Cl the more useful the time settings become For just experimenting one of the poorer quality units having a 20 percent tolerance is fine But if you are serious about using the unit for testing or in some application where timing is all important then you may want to consider a tantalum capacitor The Adjustable Timer circuit has been b
20. audio cassette player port and a telephone jack to be used with the internal 300 baud modem The unit is powered by ten AA alkaline batteries which allow 8 10 hours of operation An AC power converter is supplied for use on standard 117 VAC lines The portable ZP 150 lap computer priced at 995 00 and available through Heath Company and 64 Heath Zenith computers and electronics stores nation wide is just one of over 400 products offered in the latest Heathkit Catalog For your free copy of the Heath catalog write to Heath Company Dept 150 586 Ben ton Harbor MI 49022 Don t spend a fortune buying a tachometer build your own and save Displays engine speed in an analog form in an illuminated row of LED s In structions included a great kit Cat K 3240 M 84 9 detis POOP SNPE iN Masthead Amp Don t put up with lousy TV we can t do much about the content but this kit should fix the pix Reduces or even etim inates snow also great for reducing ghosting Covers both UHF and VHF TV Bands plus FM bands Includes 1 1 OV sup This alarm senses the voltage drop in your car s electrical system whena thief breaks into it Visual warning for thieves so chances are they will not even attem break in Cat K 325 main alarm system Cat K 3251 Ultrasonic Detector The problem with 9996 of car alarms ts that they cannot prevent the thief who breaks
21. board to the Amplifier You can also use the Amplifier circuit to make a signal tracer to troubleshoot other audio projects or equipment for 9861 83d NYf o HANDS ON ELECTRONICS o NO Fig 5 The signal tracer probe can be nothing more than a plug connected to a length of wire or probe tips may be soldered to the free end example a stereo amplifier that works in one channel but not in the other Where is the fault By connecting the input to the amplifier to a probe you can trace the circuit back from the speaker toward the input of the dead channel until you find the point where the signal is picked up Obviously the fault is somewhere in that vicinity Then using your multimeter you can compare components and voltages between the good channel and the dead one to identify the component or compo nents that need replacing simple isn t it Fig 6 By connecting the Amplifier s input to a probe you can trace back through a circuit say an audio amplifier until the point where a signal is picked up thus allowing the circuit to be used as signal tracer A word of warning This amplifier is ideal for use as a signal tracer in 99 of the solid state transistorized IC etc cir cuits you are likely to come across However it is not suitable for a lot of vacuum tube circuits Apart from that vacuum tube circuits contain a lot of high voltages if you re not careful you might get zapped Ke
22. broken axles failed brakes Bro Reader Willis Jones of Terre Haute IN there s a 50 cent bet riding on whether or not anybody s ever called him Indiana Jones says that he d give anything to find out what frequencies are normally used by the tow trucks Well Indy err I mean Willis we ll gladly take that nifty ark in exchange tor that information but us in mind next time We like to seek out these dispatches ana operations on 150 815 150 83 150 845 150 86 150 875 and 150 89 MHz Auto clubs offering such services to their re spective members normally operate on 150 905 150 92 150 935 150 95 150 965 452 525 452 55 452 575 and 452 60 MHz It s a good bet to tune those frequencies when the weather changes from bad to terrible snow storms sudden down pours rapid freezing and the like Here s a bit of scanner related trivia connected with tow trucks In many metro areas some of the hook owners are just a shade on the unscrupulous side and ride around in their vehicles monitoring scan ners tuned to the above listed frequencies When they hear a report intended for an other hook they try to rush to the scene first and beat out the hook for which the message was intended The scanners used for that type of monitoring are usually hand held portables and such a device is commonly known in the trade as a mouse because of its appearance with the whip antenna Leo Farnsworth of Te
23. di odes All new long leads 6 00 ppd STAR TRO NICS Box 683 McMinnville OR 97128 THIS 18 AN EXPANDED TYPE AD WITH A TINT SCREEN See how it jumps out on the page To order your ad in this format calcu late the cost at 3 75 per word for the x panded type and add 25 for the tint ee He RR SOROR SOR RS RR CTITPITD Bidet PLANS KITS DIGITAL Klock Kit plays 1 of 12 melodies each quarter hour Displays time date and other fea tures Send 2 50 for assembly plans and pricing to KERBER KLOCK KO 36117 Hillcrest Dr Eastlake OH 44094 CATALOG Hobby radio broadcasting CB lowfers Transmitters linears active antennas converters scramblers bugging devices more PANAXIS Box 130 HO7 Paradise CA 95969 BUILD this five digit panel meter and square wave generator including an ohms capacitance and fre quency meter Detailed instructions 2 50 refun dable plus 50 cents BAGNALL ELECTRONICS 179 May Fairfield CT 06430 INCREASE power output of Amateur Band convert ed CB radios Complete instructions 6 00 May be illegal for use on CB band CA residents add 6 5 CAS ELECTRONICS 1559 J Amar Road suite 456 West Covina CA 91792 ETCHING tank Complete easy to assemble kit Temp controlled self agitating for quality PC boards in minutes Send 74 95 to QUINTEC ELEC TRONICS 444 Lincoln Blvd Dept 225B Venice CA 90291 MASTERCARD AND VISA are now accepted for payment of your advertisi
24. discount for same ad in 6 issues within one year if prepaid NON COMMERCIAL RATE for individuals who want to buy or sell a personal item 1 00 per word prepaid no minimum ONLY FIRST WORD AND NAME set in bold caps at no extra charge Additional bold face not available as all caps 25 per word additional 20 premium Entire ad in boldface add 20 premium to total price TINT SCREEN BEHIND ENTIRE AD add 25 premium to total price TINT SCREEN BEHIND ENTIRE AD PLUS ALL BOLD FACE AD add 45 premium to total price EXPANDED TYPE AD 1 85 pe word prepaid All other items same as for STANDARD COMMERCIAL RATE TINT SCREEN BEHIND ENTIRE EXPANDED TYPE AD add 25 premium to total price TINT SCREEN BEHIND ENTIRE EXPANDED TYPE AD PLUS ALL BOLD FACE AD add 45 premium to total price DISPLAY ADS 1 x 214 135 00 2 x 2v4 270 00 3 x 214 405 00 General Information Frequency rates and prepayment discounts are available ALL COPY SUBJECT TO PUBLISHERS APPROVAL ADVERTISEMENTS USING P O BOX ADDRESS WILL NOT BE ACCEPTED UNTIL ADVERTISER SUPPLIES PUBLISHER WITH PERMANENT ADDRESS AND PHONE NUMBER Hands on Electronics is published bi monthly therefore copy to be in our hands for Jan Feb 86 10 4 March April 12 4 etc HANDS ON MARKETPLACE FOR SALE MONITOR CB crystals 1 00 each in quantity over 7000 in stock Free list G amp G COMMUNICATIONS Main Road Stafford NY 14143 ELECTRONIC parts 600 resistors capacitors
25. mitted in its true form during the first half cycle followed by its compliment during the second half ments if assembled properly Even the relay chosen K1 is an FCC approved component and I urge that it not be substituted unless by another qualified FCC approved relay Relay K1 and resistors R11 and R15 Fig 2 form part of the interface and are primarily used to temporarily fool the tele phone network into seeing an off hook condition after the access code has been entered Remember that the telephone network identifies dial pulses by current interruptions With R11 and R15 ohms across the telephone line any number can be dialed and the microprocessor can then process dial pulses with no telephone network interference That state remains valid for approximately 20 seconds then the telephone net work injects a vocal message that informs you that you have dialed a wrong number or Please hang up and re dial Refer to Fig 5 Anyway without that part of the interface it would be very difficult for the Control System to differentiate dial pulses from telephone network interference Building the Control System The patterns for the components and foil sides of the circuit board are shown in Figs 6 and 7 respectively A pictorial diagram which shows the parts placement on the circuit card is provided in Fig 8 The circuit board has been designed to fit into Radio Shack s 6 x 3 6 x l amp inch economy case When installing
26. nt 51 B6 rc a 3 5 r 2n 2 50 20250 a ie jns Lm UE aal eh Sith J pmscider tal you 50 370 s500 1 2Wan x 3 0 onn hr Sm omn usa 6438 f P2025 68 v 5 3 39 A20 74L 5249N 10298 3 179 7 zaa B C388 18 pn solae rail q 57 5 521 o NO 10 1 58 B4 36 P2026 10 10 y 3 FIAN 156 100 188 4S 188N 248 lt 40 52 n 4 405 3375 30375 741 5281N 10308 CSB2G 20 n solder tail siento urnas n END MU ON Palis 180p 500 13 v P2027 15 9 68 i 63 745189N 375 a god 63 590 570 25 BA 37 2 59 510 3250 382 Nel LCS 5 1031B 220 7 Jat2EIN 263 C9822 2Zpnsouwrial goa 70 660 6400 1 8 Wen Carbon Film Assortments P4202 1 500 pf 100 58 EE 37 paa 27 Be Em 159 32250 125 7415257N FEM oe 438 gap 4528N 248 09ES 24 pin soior tau guild 7b 72 jo Qoi STZ Seach of the 73 standard values in senos 99 90 Mecum 2200 t 00 58 epi 37 57 et x ih u 9 53550 225 2 29 22 5289N 375 C9828 28 pin solder ja m 7 10 12 15 1B 22 eic through 10M 4 3300 pl 100 58 01 4 0 2 9 828 57 1 s ated x es ach E 750 13 0 u 37 5 P7001 68 10 309 t9 A 4 so408 170 Ph zasan 253 C940 40 mesoldertan gold 112 9907 37 1365 totat pes e4206 1700p 0 58 s IEEE S 50 uU 125 d 2 37 00 a amp 800 pf 276 2370 19750 1777 90 56 CMOS iota 175 3 of 74S4728N 29 RS212 5 each of the 72 standard values in sec es 98 90 oe 300 p Tu m 6 00 46 00 P2083 so 3 0 455 3900 12600 292500 ig PRU Pul e azl saaan ax WIRE
27. os TIN MA in ic 3 1 8 4 o oN 1 1 3 5 8 14 OUTPUTS 1 2 6 7 9 19 12 4 AND 13 INPUTS EEE SAIS OO 3 GOES LOW WHEN OR 2 OR GOTH 1 f a __ i rais i i ee s 08 du 6 0 13 2 60 A05 SU ates ie D o bL d ud b elus ah E CES B PP rr 5 GOES LOW WHEN zr qu a a LL pd eee som B4 75 SO E T i GO HIGH Lise MON MANC epo MEME MEC Ma 8 GOES LOW WHEN gt O ee nel jr i y OR O OR GOTH PE mare reenen veas qe XI s E DE E E 160151160 IAO GO Hic t TES d f 4 GOES Low WHEN L i 09 m TH 6 IZ OR i3 OR BOTH nw Go N x 78 B d GO HIGH i p RES DEVICE IS QUAD i i INPUT NOR GATE IC Tene we Mna MA om de x ee ps ASAP t ees i ms MM MA Hee MA a weed eo en Nc i 30V APbLIEC ns id E 8 f n uec e E Z up n p Sd i E toe amp s we m a d wae Petes d iw mM 56 ND 5 6 ues x D s e T i 1 j i i d EET E 1 BRA RARI AERA n E en dec qm po e RA ARAS w Y wok ts i Diese f i 3 2 T m 14 ii ND 29 I4 c X ae a r ve Mee OMM Mr ccc Oe ee tages i 1 E E i i i 1 f e Po M 0 GND UE 2a Oe ES E zh j 4 OE E E E re a a S err re ee eee GND Fig 2 Completed signature chart for an unknown IC The IC turned out to be a quad 2 input nor gate HANDS ON ELECTRONICS C3 e will only draw 30 mA milliamperes Remove the resistor and re connect the current meter only when it
28. p DIGITAL OFF Lr Rs Eg s Become co ERANSDUCIR PROJECT pu ERE ay BARRY ba HAWKE 2 1531 List 17 95 1719 1245P List 16 95 paper l ai pr d CAIS M REMOTE CONTROL A MASTER Miri l gsi A It OK a M Cun re 1690 ie nes Scc a Sup 1685 List 19 95 List 21 95 List 21 95 List 21 95 List 14 95 paper Im m WEXHRC ONCS INTEGRATED VIDEO READING i CIRCUIT i ELECTRONICS SCHEMATICS ai sil aus adi j TECHNOLOGY EM C LE B X du ES i T3 OR pd 1553 List 15 95 1536 List 14 95 List 12 95 paper List 17 95 List 12 95 paper BEGINNERS GUIDE emia et TO TY REPAIR ose tits FR EE guide to ng my suec etma ahon pp oe Do el za tkn pris agr ymo oe Dar Y a mail order sources for electronic parts and components COMPUT RS HE TTE A 6 95 Ce 1909 1577 1599P 1218 1539P 1013 y Ope See List 21 95 List 19 95 List 15 95 paper List 18 95 List 15 95 paper List 14 95 Value i Se C y us cn a MEL OEE a FREE When You Join Now TO z Fhe Te e 7 very good reasons to join the Electronics Book Club Big Savings Save 20 to 75 on books sure to in crease Mai electronics know how No Risk Guarantee All books returnable within 10 days without obligation Club News Bulletins All about current selections mains alternates extras plus
29. proper trigger selection or incorrect inter pretation of the time base or vertical attenuator settings Other errors are caused by a lack ot understanding of the equipment s specifi cations For instance using a 25 MHz scope to examine a 100 MHz signal But if you keep in mind the points we have made in this article and those that pre ceded it all those errors can be left to someone else to make L Digital Course Continued from page 105 11 It takes clock pulses to shift one byte into or out of a shift register 12 A long shift register has a 6 bif word counter whose output is called a n Itcan store bytes The shift register length is bits ANSWERS TO THE ABOVE QUESTIONS SuqziS v9 x 8 S YSU 19481681 uius au eiq sed syig g Iy Se1 q 10 spia v9 Soje3ipur SSOIPPe 1iq 9 S5a1ppe Zi liq sad Sbo g LU NO penos ur jajeied p NO eqered ur Enes i jno jayesed uy serere q yno euas uj euas Of mnuanbpass 8 6 jeuumepl 100Lq 8 uaz LZ xox zex pO OXSX EXE LOLL OLEE ELLE 0000 1000 0L00 9 seuin xis pausu 0109p S g euiusep LLOO LOLL P Bip yoga Jaj aunoa GOW euo s p S ZHAS 08 ZHP OOP 08 Ob x 8j5 8 0 e 161 01 AQ 16 unoo GOG eui BAG sapiap a3junoa Ji e eut 72H38 b Jg L Bel L 2x exgxd k 2z d E ex g cro 90k 2 Z 2 0100 IO BL 2 7 h ium TTL
30. queste A Single Enaec with Mate Connector 149 95 B Singla Ended with Female Connector C Doub Ended wih Maie Connector D Doub Ended with Female Connectors Double Ended One Male amp One Famaia Connector as ahe 2 Pn Submniature Assembiias Dige Key Pricing Styla Par No 1 10 100 1 000 28860 62587 50 H6Ot 5 ND 17 4577 R606 10 ND 647 872 35800 321250 R604 25 ND 1037 9177 58880 5087 50 Ris 50 ND 16 87 14927 36860 831250 30980 277500 R708 5 ND 655 4922 A70 16 ND 6865 672 39560 340009 RI 25 ND 1076 9522 RIGO 275 00 H7G BONO 1726 15272 98960 BA 00 R6G8 5 NO 905 8004 497 20 145000 RECS 10 ND 1035 BIS 56720 50 500 R amp G 25 ND 1425 12604 78720 695000 ABS SOND 2075 183 54 125320 1097500 A7GK 5 NO 983 BM 4825 00 RIB 10 ND 113 a 5450 00 R7G325 ND 1503 13294 7325 00 R7GS SO ND 2753 196 44 450 00 R6725ND gu B3 49 ABVIOND 1075 MA Rb 225 N 1464 12939 79820 186 99 1253 00 ture Assemblies zd 7 Roi 10 ND 8358 528 76 R6C5 25 ND 138 23 B9 40 iaaii RES 50 ND 22931 1485 B0 R706 SND 7020 437 78 Style 0 J R2C5 10 NO BB 1 548 16 A 25 ND 14306 B90 BO R75 5 ND 234 14 1485 20 12 825 00 Number Atte Dash y Cable Langth In Inches a RB403 35 ND 284 25 02 22408 Con DIGI KEY Pricing R6410 38 Nl 3H E 30070 2818 0 ft cta Stra Part No 10 100 Pa n Past wa REGS 5 ND 11252 69488 621500 Sakr Tas Rregrmmable Liara Modules a amp i 10 ND 13073 980676 7205800 88411 36 AU 48
31. through UIO That turns on Q5 and a 1 is displayed on the hours readout Thus we ve now gone from a 9 to a 10 The count continues until the hours and 10 s of hours readout displays 12 On the next hour count the clock must display a l for 1 O clock With the 10 s of hours counter U6 outputting a high at pin 11 the next count causes U6 pin 6 to go high which then causes U9 a pin 13 to go low and U10 pin 9 to go high After inversion in U8 e Q5 is turned off and the I0 s of hours readout goes out At the same time U9 a pin 13 also causes pin 10 of UIO to go low That in turn triggers U18 a pin 11 and causes a positive going pulse from pin 10 to be sent to U6 pin 1 preset enable U6 had been preset to a 1 soa l is shown on the display Power Supply Figure 3 shows a schematic of the recommended power supply You ll notice that there s nothing spectacular about it In fact except for the tap off the secondary of the power transformer it just like what you d expect to find in any other construction project The tap off the secondary feeds a volt age divider network That network is used to attenuate or lower the voltage from the transformer to a level low enough to be used by the counting circuits It is from that signal that the clocking frequency is obtained Fig 5 Full scale foil pattern for the component side of the Clock s printed circuit board If you decide to etch your own board contact transfer film may b
32. 0 66 is typical commonly referred to as the velocity factor In the theoretically perfect situation where the cable is correctly terminated all the energy is absorbed by the load there will be no reflected wave and the voltage and current values will remain essentially constant along the length of the line Such a situation is said to constitute a flat line By now the reason for our interest in the SWR should be apparent Because it occurs only if there is a mismatch and its value is directly related to the degree of mismatch its measurement provides a very useful suck it and see ap proach to ensuring that the transmitter is presented with its correct load In greater detail an SWR of 2 tol will mean that the load is in error relative to the cable impedance by this ratio But it cannot indicate in which direction the error lies Assuming a 50 ohm cable the 2 to error could mean that the load is half 25 ohms or twice 100 ohms the correct value Note however that the relationship is true only when the load is purely resistive Considering all the foregoing and with the benefit for hindsight one wonders whether the term SWR to some extent might be misleading and that some other term like mismatch ratio might not have been a better choice SWR LOSS dB But it is essential to keep one very important point in mind at this stage of the discussion the existence of standing waves in itself is only a secondary problem
33. 000 hz 32 00 hee T Power rating 15 watts max ee Drilled to mount line matching transformers 25 00 each D m COMPUTER j GRADE CAPACITORS 2 000 mfd 200 VDC 134 DIA x5 HIGH 2 0 3 600 mfd 40 VDC 1 DIA x 334 HIGH 1 00 6 400 mtd 60 VDC 1 DIA x 4 HIGH 2 50 9 700 mtd 50 VDC 1a DIA x 412 HIGH 3 00 31 000 mfd 15 VDC 134 DIA x 4 HIGH 2 50 72 000 mfd 15 VDC 2 DIA x 438 HIGH 3 50 CONNECTORS ALL ARE 1 56 SPACING ny nmi EISE rs m TUM UO m COOITTSEITUTITTTTASHTTITTISHT IT 22 44 EDGE CONNECTOR PC style 2 00 each 10 for 18 00 22 44 EDGE CONNECTOR solder lug 2 50 style each 28 56 EDGE CONNECTOR PC style 2 50 each 10 tor 22 00 36 72 EDGE CONNECTOR PC style 3 00 each HANDS ON ELECTRONICS RO 185 000 mfd 6 VDC 43 86 EDGE CONNECTOR 22 DIA x 4 2 HIGH 1 50 PC style 4 50 each TI SWITCHING POWER SUPPLY Compact well regulated switching power supply F designed to power Texas Instruments computer equipment Tz bd ES p wt 7 i Q INPUT 14 25vac tamp t p IyL3sli OUTPUT 12 vdc 350 ma Tes ni dro 5vdc Q 12amp Era i 5vdc 200 ma Mes Tre a menace FA SIZE 434 x 4 4 x t a high SPECIAL PRICE CASSETTE MECHANISM 5 00 each DUAL L E D DISPLAYS j UHT 560 high 7 segment L E D read outs Mount in 24 Din DIP socket FND 5148red c c 75 each DL 527 red c a 75 each STANDARD JUMBO DIFFUSED T 11 2 RED 10 for 1
34. 1 CLOCK INPUT R36 R37 e 100K 82K 12V REGULATED At the same time the cathodes D2 and D3 are pulled to ground causing pin 4 of both Ul and U2 to go low and blank the seven segment Also pin 13 of U15 goes high forcing pin 2 of U17 a to go low turning Q4 off The signal at pin 13 of U15 is also fed to Q3 is turned on causing the display to show BEFORE Note that it will be blanked for one count through D5 to avoid having 13 BEFORE and 12 30 on at the same time At the next count the display showing 30 goes out and BEFORE lights and remains on for the next half hour The clock now reads 29 BEFORE the next hour whatever that happens to be Note that D5 and D6 must be germanium diodes to effectively inhibit A low from U17 a pin 2 is fed to pin 10 of both U4 and U5 causing those units to count down Thus the first 30 minutes of the hour has been decoded and the Clock now begins to decode count the next half hour EN Fig 3 Schematic diagram of the power supply for the Clock circuit Note that aside from the resistor network R36 and R37 which provides timing for the Clock there is nothing unusual about it Although a bridge rectifier is shown there is no reason why discrete diodes cannot be substituted With the BEFORE lamp still lit and the counter count ing down the count continues until the hour is reached the hour the Q outputs of Ul and U2 are all low the seven seg
35. 170 st 3 8 4 B3 706 5878 Pert No mf 1 10 10 100 4 5 p 923 92 B7 555 B2 84 6532 1 Hus s p E Es ES Se BIiEsRSE Arn Bajas com 2 o oj sl 74 T 300 3 4509 00047 nos 7 1 S5AN a5 IM 3 D436 C70 Stauc RAM 22 Dip 35 00 107 047 B3 18 154 C283 73 5 12 3932 P4510 0 0056 M m 2 2 siam 74LSESN amp i D4364C 200 Siam RAM 28 Dip 732 f ee 3 18 154 2283 13 192 932 Brasi2 00082 e 741873N 55 TOAOISU 153 O2764C EPROM One Time Noe Deacription Pky 10 100 1 000 10 000 e Wen fe a la 154 1283 ta 11B 962 TON 789 5740 24L874N TDA 5S20U0 502 Programmable 2 Di 465 1400 1V Y E 3 Operantg Temp Range 55 C ta gt 14 77 15 25 1035 bp FALEN p TDAIOTOAU 151 0275407 EPROM Uia Violet D dee Herde DO4 80 joo 6000 sonf Ls Coar ete les a7 B o 2p te E 4 wsb 5 e Uo 9 78 5a J4LS76N 55 NESEN 362 F ssahte 28 Di 239 B inao03 200 Piv pp 41 80 00 6000 54000 p Coa wient 306 PPM 10 amp 3 28 234 1953 18 550 1543 pen 0012 s M 808 5a90 JALS78N 60 RESON CSREES CEPADM ODE UE INADA 400 PIV HL Nol ag muB rem 220 490 3 G V iu wo 75A jee i CRA EE AE PITT P tl 7 E x x 324 ig P4516 6 018 JALSB3AN 96 BjPCEZIQUN 5 491 772566 rd vi hola zD 78 18005 600 PIV 0041 00 5900 7400 62500 f 5 Wiewounn Rectangular Resist if 6 53 45 3 82 BA B 2635 z 8 1 uN B75 S370 2 M s PEN S RESON eGo EPROM Ultra Vale EE SOPN GONG gon DO GIO oxxezep b Wa veecox3nn Pet tink ae Bat Ed m MAE oS OL r e p E att Va 3 k 7ALSBEN Er ae ps DICBO 25 EPROM U
36. 1N5296B 1852574 HC 33 EYE s M4 10237 MA102348 MA1023K 14753A agun 189578 equ 1N95BB tQuv 1N8598 ryu op Littelfuse Fuses 34G NORMAL BLO FUSES DIGS KEY Part No Reg b F100 NO oro 15 Q F10 ND 03 1185 F102 ND 062 440 F103 ND 100 440 104 ND 125 440 1433 c3 F105 ND 150 e 4 91520 ng 18 F106 ND 40 ve f F107 ND 4 40 pos EE F108 ND 5 Doo c 18 t109 ND 5 ngs C 18 FIIOND 5 1850 C 18 FIN ND 5 994 C 8 117 ND 6 000 C 18 F113 ND 54 18 F114 ND 8 5536 18 F115 ND 7 3728 18 FIEND B oo C 18 112 ND 3 2160 1a F118 ND 10 000 gt 18 F119 ND 11 98135 gt 18 F120 ND 2 000 18 z F121 ND 1N4728A Sunas 5 5 F122 ND aes nue 10 F123 ND 18 600 18 200 124 ND 18 a AC 18 F125 ND XK 000 c 1a 22 1184 HC 18 F126 Sr Ht z as Dn 10 x054 73 400 nc 8 x085 38 DO C 18 3AG SLO BLO 2 32768 KHz Cst 1 72 50 10 180 QU 100 Amp FIBER OPTICS Price 400 226 50 178 00 66 00 INS RUM equry 7 1 961B ens Amp M M UNNIOODQOOO mDmmooooaocmcuomcO rm2n2i NWN 2 NEENE MUN ie Raia 2 BND 196 1740 14050 J 4 RB417 18 ND 73 19 BD 138 1 1 28 RB8412 38 NQ 253 234i 362 IE 2H R84 36 ND 285 235 1828 80 Big 2B R8413 18 MD 102 2685 847 20 Ey 4B ASAI ZENE 358 431592 24940 717480 2B R84116 NO 113 2785 2 895 191115 48 P8414 18 NC 363 3223 patie 508g 2B RBA14 3G D 436 38 8 30088 782096 B 6 2B RHAIS SNO 38B 34s6 268 2 222964 gE 8 RB1 S 18ND 452 4017 31126 2710 16 28 88415 36 ND ha
37. 2 50 U 5 2 95 CAN DA JANUARY FEBRUARY 19 6 TRE MAGAZINE FOR THE ELECTRONICS ACTIVIST Tearout RII eT Leo information Start your collection toay Give the unknown DIP a name A 17th century card game that s gone digital Discover what and how importam it is for getting the sigral out Displays time the way you Say t nS 71896 48754 M MMM M M M M t eee eee THE ANSWER BY ANY MEASURE 22 13A 2215A 2235 DUAL TRACE OSCILLOSCOPES IE Now Tek quality and expert advice are just a free phone call away The industry standard in CRT performance Crisp easy to read bright CRT 14kV accelerating potential provides high writing rate and smail spot size Full size 8x10 cm display for measurement accuracy Display controls are flexible and easy to use Sep arate iniensity controis reduce blooming in alter nate sweep mode Focus tracking minimizes control adjustment and BEAM FIND elimi nates confusion Vertical sys tem provides measurement assurance Fia transient response and high accuracy ensures true reproduction of your signals Fast risetime and high bandwidth is well suited for a variety of measurement Perform delayed sweep measure ments accurately and easily Both sweeps can be displayed alter nately making dif ferential measure ments easy and accurate 1 An interlocking SEC DIV cont
38. 7 7 22 16 180 00 ach of values to 29 96 3300 10 99 8 n j md lt Olyes er cit 1 74184 1 2924N 239 A 15CCN Y 2 a5 38 90 471 AR apacitors Mew dese o crmbunceew 022 Landen 123 ADous7C0N11 25 aero Bm mo TE asse da 10 0 126 1094 9138 113 968 062 4188N jamas 2 Lb 2 z LM30BON 135 ADCDRRGICCN 525 2 23 2520 890 1205 RSXB Seach o values 100KQ to 1 COMO oa 2000 10 55 1326 11052 154 1320 109 40 DG KEY Worning Pak Pak Of Pek Of Pak OF 74190N voe p4siesn 375 Caos sa iMan as aocwotceuz to L7 E ve i wem 480 total 9 ee oe ee MIS Part Me Vehuga jif oOo 10 t0 ond SUN O HC2BON 180 LM3083 a9 ADCIOZTCCNS 00 i 45 42 36 0 330 00 9 16 18 555 1289 139 08 2103 280 0 9 T B 74191N a w 289 x 4 8 94 19 164 1368 12308 74192N io 74S17N nTa ORA raso is vais 1 10 ADCaBTICCNID 5 zt h 4 420 0 FH u MN wi wu 3B NES ge 2129 250 02 19 16 1368 2308 FRIN 108 A ASISIN 5 SOB NC 25 FaN ces ivaxoN gef ADCINCEN S ss PS 48 455 3900 35 50 0 e m trou wW uo eris Ole Pi De EE LUAM 74194N LOB vsuoN 220 ancen cope ees 10r Apos 7 moe L QD ee EX o 1 mom 89 n 5 ta 2 TOT A D oM ue 145 74195 745188 LM36Z4N 4 aj ADDTMICCN1S e f M E 6 630 woo 495 1 t3 80 022 19 16 3 amp 8 123 s amm arjane cm om ce 1 DACOBDOLCK 3 38 MW 182 B5 870 S25 12 65 32 29 5 5 xe lem Zo mo B 16 He EE d 7AS184 2 IHG 9 RANT N 56 J LM3S05N 659 DACOBO7LC M jE3A 9 n 665 5 ef 4 19 64 1368 230
39. CRT and the high voltage wiring There s just no way around it so make certain that you use a very short miniature screwdriver re move any rings or watches from the hand that s used to hold the screwdriver and be extremely careful If you ve never worked around a CRT before wearing a rubber glove is suggested when making the focus adjustment To the trained eye the Heathkit HVM 122A had a slight degree of barrel distortion which was not evident on two factory assembled Zenith monitors that we used for com parison The monitor was connected to the IBM PC AT ard Apple II for comparison The images were typically crisp ar d sharp from edge to edge The monitor will work equallv as well with other personal computers such as the PCjr Apple III all Heath and Zenith models Compaq TI 99 4 and Atari 800 and 1200 Remember with a monochrome monitor the TV set will be freed for the afternoon soaps and weekend ball games IH DIGITAL FUNDAMENTALS We look into the sequential logic circuits and discover what makes binary counters and shift registers do their thing LESSON 5 Understanding Counters and Shift Registers By Louis E Frenzel THE TWO BASIC TYPES OF LOGIC CIRCUITS ARE COMBINA tional circuits and sequential circuits Combinational cir cuits are made up of logic gates connected in a special way The outputs are a function of the inputs and how the gates are interconnected Sequential circuits are made up of both gates a
40. It boasts as many myths and old wives tales as does pregnan cy and childbirth some of them perpetuated by supposedly reputable text books In trying to get a mental picture of what is admittedly an extremely complex subject it is often a help to start with a theoretically perfect situation against which we can compare the usually imperfect practical situation The Antenna Let s start with the antenna In any transmitter installation the antenna has to satisfy two basic requirements One is to radiate the RF energy fed to it by the transmitter in the most efficient manner possible The other is to present the trans _ mitter with the correct load in order that the transmitter may deliver the level of RF power which the designer intended While both are important the second requirement is in many ways the more important one Suppose we have a typical commercial transmitter designed to deliver 10 watts into a 50 ohm load If we connect a non reactive 50 ohm resistor directly across the antenna terminals or socket at the set and energize the transmitter it will deliver 10 watts to the resistor which will appear as heat If we were to substitute some other value of resistor a number of things could happen The most likely one is that the transmitter would no longer deliver its 10 watts By how much it would fall short would depend on the error in the load value and the design and tolerance of the particular transmit ter outpu
41. It is a useful measurement only because it tells us whether the transmitter Is being correctly loaded or not and that our efforts should be directed to correcting this aspect of the problem Whether we correct the SWR in the process may not even matter Let us consider a practical example Suppose an SWR meter reading indicates that there is a serious mismatch between antenna and cable We have two options either fit some kind of matching device between the antenna and the cable so that the antenna now looks like the correct value or fit a matching device between the transmitter and the cable so that the transmitter sees a correct load In theory the first option is the preferred one since we not only present the transmitter with its optimum load but we eliminate the standing waves at the same time In practice the second option may well be very much more practical and convenient It will have achieved the same primary objective of loading the transmitter correctly and in many cases the SWR can be ignored But what happens to the RF energy reflected by an antenna which does not match the cable If it is sent back down the line is it not wasted No it isn t The practical situation is that the transmitter presents a gross mismatch to the line and deliberately so Its source impedance is kept as low as possible in order that as little as possible of the RF energy it generates is wasted as heat in the final stage So the reflected RF e
42. MAIO26B Aleem buzzer tor MA1026M MAIS26K MATD2 M P T B For additonal sensor units you ifl need LM3342 Temperature Sensor K4A32 300 anm Poteotrometrr 302P 8 Normally open SPST Switch B5 4 25 610 IP C UM334Z poten 10 262 50 MX HNN 78 7U 7O UO DO t0 tA LA p U QD U5 MA 1026T 12242 138 0 154 37 164 2B 200 26105 110375 1243 50 1388 00 1877 5f 8 75 225 280 7612 50 12 862 50 3915 00 4905 00 7875 Q0 ERBHUCEENNNEGG gBEBUdaEBSEEENEN ha Mj J R AJ IRI RI RI 2 NI AJ Rf MNNNMENMUNEMMNNAMM E 3 5 3x5 3 B ava 5 dad 5 4 45 1092 Poem Contacts e 29 3271 4 36 827 Dual Color Oranga Green Diftosea 1399 2 E 0 Round QUARTZ CRYSTALS Digi Kev Freq Price Part No MHz Esch X045 OX 12 3 16 axo 5 45 1 000 766 65 B53 2 939 BF t026 5C 1143 amp 766 amp Ma lime and seen time R6 3 SND 11739 H428 647750 Bartery back up in case of power failure pari 10 ND 135 56 835 16 7467 50 Typica applications include Ck racio tmr R6 3 25 ND 1902 125780 1033758 clock desk clack instrument GENAI clock and BB5 3 50 ND 28129 1842 20 15 387 50 more 25 Pin D Subrminiaturs Assambites dis many Casa nc 33 MA1020 0 384 INCH HIGH DIGITS HC 18 gra EU NO Tee 1841 60 15 650 00 Display hours and routes minute and seconds aiarmi A510 36 ND 798 051 4348 3837 56 14 14 14 R104 12 ND R104 18 ND R104 24 ND 13 86 15 45 17 05 853 2
43. SEON PAK CA2N 125 UMIINBO 179 Par Pree bigis wi wteppuig RS160 5 sach of tha standard values in senes 9 90 ie p n 103 8 89 667 f porta 15 25 ai 270 2250 202 E ca Heic JaHC73N 9 MES ge copan c3 SOIC ES OB GOCO 10 1 2 15 18 22 eic through 1 0M Pix Ge le 180 8853 P205 2 25 34 294 2450 29050 i amp BILSS7N TANGON SOL 393N zb COPS44LA 7500 TEXAS INSTRUMENTS QUALITY SS opes 5410 68 a 500 l 2 i 53 p 3 5 i 5 ms N M 1 e 7 7 2 63 95 50 t M395e 229 COP O0N 213 RS260 Sep h of the standard valuasim seras 1 990 P44 82 pt wn 205 17 58 13 P2048 68 25 58 510 E m 75 7AHC7 N 95 bor Mv3ssT 275 COPASEN 538 TIN PLATED WIRE WRAP mm 200 Micrcaches Tin 1 3 16 20 24 etc through 910K 360 Panas 9 25 a 705 5875 52875 DRM 1 5 1 gg ft M35 g gaf CO 299N 538 B Part wo Description 1 L 100 total pcs bal ae Specs on Physical Size and Electrical ee 15 129 1110 9250 83250 M396K DP amp RM2N 378 BCBS B pin wne wrap t 3 aractecigtica consult your FREE DIGI KEY Catal 5 1 80 1545 12875 1158 75 a MHCIN E LMGERC v RO breen 350 cena pm wre weap Ps e d d 1 Metal Film Fixed Resistors ASSORTMENT OF IE e9 252 3 25 255 2 90 19250 154250 x 4 n 3 13 LM556CN 32 D 8224N 450 CBI 6 16 pn vere wrap v 57 56 550693 abito in 1 4 wen POPULAR vLUFS den d o 127 38B0 30500 27 4500 E 74HC112N 95 XlMs scN 2aa 0r amp 226 350 ceno sepe em wrap t x 1 PANASONIC QUALITY 25 665 5700 7500 4275
44. The projects are based on those selected by the Editor from the Dick Smith Electronics catalog assembled and reported in detail in the section Since the parts are supplied in kit form their availability is assured should you not be able find them in your junkbox or to purchase them locally The parts designations are not consistent with those usually used in this magazine For example TR is the symbol used for a tran sistor in this section instead of Q The reason for this change is to permit the Parts Lists and diagrams to coincide with the printed material supplied by Dick Smith Electronics We have provided more information instructions and diagrams than we normally would do because it is the inten tion of this section to encourage neophyte and novice builders to get totally involved with their hobby The old pros are urged to read a bit faster and plug in the soldering iron immediately Happy soldering E MULTI PURPOSE FLASHING oe r A NE g Nm i E es This simple circuit can be used in almost any application everything from warning indicators to jewelry to decorative window ornaments anything else that you can think of LITHE MULTI PURPOSE FLASHING LED A SS project can be used as a simple warning indicator outside a darkroom door for example Or it can be used to warn a thief that your car is fitted with a burglar alarm R1 even if it really isn t Or if you re so 3302 inclined you can turn
45. are from a single manufacturer and are designed for use with a single computer an IBM compatible There is at least one hard disk unit available for every conventional personal computer Identify IC s Continued from page 38 ULL Pidi Vr N 5 i 4 a v 75K Fig 5 Linear devices can also be identified using the signature chart This completed signature chart reveals the signature of a 741 op amp IC Those techniques work on linear as well as digital devices For example A signature of an 8 pin DIP 741 op amp is shown in Fig 5 Note that the low resistance row still identi fies the substrate V for an op amp and also that the lowest reading in that row identifies V The only other uncircled reading in row 4 is 950 ohms in column 6 identifving pin 6 as the output terminal The 741 8 pin DIP op amp has nominal 1000 ohm resistors from each offset null terminal to V The circled resistances in Fig 5 illustrate some interesting facts about C resistors They do not always read the same in both directions 750 200K 200K ISK 15K ZOk 0 Lr Iu TEM E s x ro umm a ohms one way 850 ohms the other pins and 4 and 5 and 4 and they may deviate quite a bit from nominal 1000 ohms given in spec sheets Nevertheless the offset null terminals are clearly identified The op amp inputs are almost impossible to identify from a signature but the information alr
46. axis of an oscilloscope display need not necessarily be time Many oscilloscopes have an X Y mode in which one of the input channels is applied to the horizontal amplifier What is the use of such a mode Well one popular use is to measure frequency and phase using Lissajous patterns A Lissajous pattern is the pattern that is generated when a sinewave of one frequency is plotted against the cosinewave a sinewave that is shifted 90 of another Studying those pat terns can reveal the frequency and phase relationships of the two signals Several simple patterns are shown in Fig 6 The most basic of those patterns the circle of Fig 6A can be used to determine an unknown frequency The circle is generated when the frequency amplitude and phase of the two input signals are identical The technique is simple a frequency generator output is fed to one amplifier say the vertical one while the unknown signal is applied to the horizontal amplifier The output of the generator is varied until the perfect circle is formed The frequency can then be determined from the generator s settings Common Errors Because an oscilloscope can be among the most compli cated test instruments to operate errors are often made in its use As is usually the case those errors are unnecessary Most errors are caused by incorrect assumptions For in Continued on page 108 Qo COO OY Fig 6 Some simple Lissajous patterns In A the vertical and hori
47. bonus offers Comes 13 times a year with hundreds of up to the minute titles to pick from Automatic Order Do nothing and the Main selection will be shipped automatically But if you want an Alter nate selection or no books at all we ll follow the instruc tions you give on the reply form provided with every News Bulletin Bonus Books Immediately get Dividend Certificates with every book purchased and qualify for big discounts of 60 to 8096 Extra Bonuses Take advantage of added value promo tions plus special discounts Exceptional Quality All books are first rate publisher s editions selected by our Editorial Board and filled with useful up to the minute information p mr ELeeraanues Book Cie P O Box 10 Blue Ridge Summit PA 17214 Please accept my membership in the Electronics Book Club and send the 5 volumes li circled below plus my FREE copy of The Electronics Buyer s Guide billing me only i 2 95 plus shipping and handling charges If not satistied I may return the books within ten days without obligation and have my membership canceled agree to purchase 4 or more books at regular Club Prices plus shipping handling during the next 12 months and may resign any time thereafter I i 800P 1013 1183 1199 1218 1241P 1245P 1277 1339P 1431 1474P 1529P 1531 1532P 1536 1539P 1544 1553 1577 I 1599P 1602 1672 1685 1690 1699 1719 1909 1992 i Name i Address City State Z
48. but not until housing for the unit has been prepared Prepare the cabinet that is the to house the Before and After Clock by first cutting out suitable holes in the front panel following the front panel visor template of Fig 7 for the BEFORE AFTER O CLOCK 30 lamps and the seven segment displays Then using that template prepare the visor through which those lamps will glow One way to make the visor is to make an overlay of Fig 7 and simply paste it on a small piece of clear plastic To make the overlay you can take a photocopy of the figure and either have an acetate film made of it or use Lift it film to transfer the diagram to the plastic Once that s done mount the chassis components wire up the power supply and then mount and connect the printed circuit board according to Fig 6 After the Before and After Clock is completely wired and all connections checked for accuracy it s time to try it out Use Now that you ve finished the construction the next step is TC 10 S HE ED 12V BEFORE AF TER to turn it on and set the time You may have a minor problem with some 4012 s The hours display should change only at 7 30 If it changes at 19 minutes counting down a 001 pF capacitor connected from U16 pin 13 to ground should clear up the problem The first thing to do after applying power is to run each number through a 0 to clear Note The 10 s of minutes display will go past a 3 when cle
49. by a key switch just like the ignition switch in a car you turn the key one way and the switch is on back the other way and it s off Key switches are normally installed on or near the front door of the house or in the case of a car on the door or fender Inside the house connected to any vul nerable door or window are sensor switches that detect any opening The sensors are usually magnetic reed switch es which we ll explain later When you leave the house you make sure that all windows and doors are lock ed then turn your key in the switch The circuit is then armed ready to detect any intruders The main alarm circuit is a normally closed type meaning that a small current flows through the sensors when the Alarm is armed If any of the sensors are opened or if the intruder tries to cheat by cutting a wire the Alarm trig gers instantly Any warning device con nected such as a bell siren etc sounds for around five minutes After which it turns off and the circuit resets so that your neighbors aren t annoyed by the noise There also is a secondary normally open circuit in the Alarm that you can use with under carpet pressure mats or con nect as a bedside panic switch in case an intruder has gained entry by a method that has failed to trigger the door or window switches Another feature of the Alarm circuit is that it operates normally from the main supply via an adaptor And if for some reason the pow
50. conventional external hard disk in that it is self contained in a cabinet with its own power supply The difference is that the external expansion unit also con tains five to eight empty expansion slots the precise number depends on the par ticular model Although the hard disk controller uses one of the computer s slots the external unit provides from three to five additional slots And then there are the streaming tape drives but that s a subject for an other time Security First The importance of being able to shut down a hard disk independent of the com puter isn t all that obvious If a computer is to function as a host for telecommunica tions meaning the computer is connected to a modem that s always connected to a telephone line someone can access the computer by simply dialing the tele phone While that is a convenient way to permit people to log in from their home or a field office it also places all disk files at the mercy of the user While the files can be protected by sophisticated security software that permit only authorized users to access specific files the use of such software doesn t necessarily stop a deter mined meddler If your computer has an internal hard disk it s always at the mercy of whoever accesses the computer the security software only slows them down If the security software is so good that it cannot be easily defeated it might prove to be more trouble than it s worth On the o
51. cost about twice as much Nice going Regen cy See the HX 750 at your nearest Regen cy dealer Want To Monitor MARS It s not too difficult to hear MARS on your scanner No not the red planet with all of the imaginary canals This MARS is the Military Affiliate Radio System an emergency communications systeni run by volunteer operators who are usually licensed Hams MARS comes in three different versions Army Navy and Air Force and the frequencies used span the unit covering 30 to 50 lock out switches tem porarily skip over un wire antenna A built in you can plug in an ear i entire shortwave and scanner spectrum with Voice CW and RTTY traffic Army MARS stations appear to be es pecially plentiful and they offer much good listening On the VHF low band look for these stations on 40 95 46 79 49 79 and 49 93 MHz When it comes to the high band check out 143 415 143 99 148 65 and 150 625 MHz Frequency 143 99 MHz is a rather active repeater output frequency the talk in trequency is 148 01 MHz Hooked On Hooks This time of the year there s plenty of activity on the channels used by those commercially engaged in relieving auto emergencies The action primarily con sists of dispatching tow trucks hooks as they are called in the trade to the scen es of dramatic accidents or simple vehicle failures trom natural causes like over heating
52. cost effec tive designs can store 2 5 MB mega bytes per side or 5 MB per disk A 5 inch hard disk mechanism providing 10 MB of storage usually has two disks A 20 MB drive generally has four disks etc The figures 2 5 MB 5 MB etc refer to the amount of user storage In fact the disks are capable of slightly more than their rated capacities but some of the disk s storage capacity is required for for marting tormatting being data that must be on the disk for the hard disk system to work Often you ll see a hard disk advertised as having 11 MB of storage 10 MB tor matted meaning that the blank disk which can t possibly be used as 1s can store megabytes But after the disk s is formatted only 10 megabytes are available to the user That s because an unformatted disk cannot be used by the typical applica tions oriented personal computer user Only the formatted capacity is available for user storage Because some of the formatting data is common to all the disks in the drive the storage progression is not necessarily linear A particular family of hard disk drives might be available in storage capacities of 10 MB 20 MB 42 MB Hard Disk Cartridges Although the most commonly used hard disk drives have the magnetic disks sealed in some manner so they are pro Continued on page 104 Hard disk drive units come in all shapes sizes and configurations This assortment of 5 inch drives
53. crib are added to the dealers point tally Thus in his own interest the non dealer attempts to discard the lezst combinable cards that hz can imagine i In cddition there is a play off in which each player lays down a card and announces cumulative total of the cards played First the non dealer cuts the cards and the dealer turns up the first card of the bottom half of the deck let s say deuce Then the first player lays down a card perhaps a 3 and announces The game continues with the next player discarding another card let s say a 10 this time announcing 15 for 2 he then pegs to holes and so onto a total of 31 points or less Points are scorec for making a total 5f 15 and 31 for the last play without exceeding 31 _ and for any scoring combinations that may be made be tweea doth players cards along the way Finally the non dealer scores for combinations contained in his own cards And the dealer scores for his own cards as well as those contaihed within the crib What we ve attempted to do here is give some of the mosf basic rules of Cribbage For a better under standing of the game you might want to pick up a copy of The Penguin Book of Card Games by David Parlett published by Penguin Books Ej MAS DO ANA ANA COUNT CLEAR RESET dia L ym a i m 7 P a mas xc r AAAA eu TON CULAR I MAA eH EE Nee a ea ee i moe ent PERI E Se ane erat rere ar sata 986 83d NVP t Tl
54. don t miss any issues and want to save 2 00 too Send me the next twelve B issues of Hands on Electronics for 28 00 Postage is free in U S For Canada add 6 00 Foreign E I add 14 00 B Allow 6 8 weeks for the first issue to arrive M Please print H I E I RUE eE B B Name Detach and mail today to i HANDS ON ELECTRONICS d SUBSCRIPTION DEPT U M Street Address P O BOX 338 l I ind MOUNT MORRIS IL 61054 p I n wll tains an impurity called copper oxide which forms barriers between the copper crystals making distortion and signal loss even worse Linear crystal oxygen free copper ca bles are made only by Hitachi Cable Ltd U S patent pending The LC OFC ca ble is available for a wide variety of audio and video applications at prices starting at 28 00 for a pair for stereo intercon necting cables and 2 50 per foot for speaker cable through audio high fidelity outlets throughout North Amer Ica BB YOU CAN HAVE THE NEXT SIX ISSUES of Hands on Electronics delivered directly to your home for only 14 00 We pay the postage If you want the next twelve issues you Can even save two dollars off the newsstand price Get twelve issues for 28 00 tronics SUBSCRIPTIONS ARE NOW AVAIL ABLE B EVERY ISSUE OF Hands on Electronics will continue to contain a variety of construction articles to suit every taste In addition feature articles on electronics fundamentals test equip ment and tools will round out
55. each issue Of course Hands on Electronics will continue to provide new product and literature listings to keep you up to date on the latest developments in electronic technology B GET IN ON THE ACTION Order your next issue of Hands on Electronics today Use the convenient order coupon below Be sure to send check or money order no cash AHOA6 Letters Continued from page 5 York Offers a variety of associate and bachelors degrees through its Regents College Those include AS Computer Information Systems AS Electronics Technology BS Computer Information Systems BS Computer Technology and BS Electronics Technology The degrees may be earned through a wide variety of methods M S Springfield OH One reader called to tell us that she is enrolled in a Cleveland Institute of Tech nology CIE course that will reward her with an Associate in Applied Science Degree in Electronics Engineering Tech nology when completed Bookshelf Continued from page 15 understanding of computer electronics while you re building those enjoyable projects As an added bonus this how to book gives you detailed instructions for doing those projects with the TS 2068 1500 and 100 computers Jim Stephens is an educator and a devoted electronics hobbyist A resident of Nashville Tennessee he has worked with the Tennessee Department of Education for the past ten years Stephens constructed his own microcomputer
56. get all the excitement in every issue o Radio Electronics every month by filling in and mailing your subscripton card today Bookshelf Continued from page 12 the original Linear IC Equivalents book shows the equivalents and pin connections as well as the country of origin manufacturer and functions of popular user orientated selections of linear integrated circuits It includes European American and Japanese devices manufactured by Advance Micro Devices Analog Devices Fairchild Harris Intersil ITT Motorola NEC National Semiconductor Philips Precision Monolithics RCA Raytheon Siemens Sescosem SGS Ates Silicon General Signetics Sprague Siliconix PORUM AEG Telefunken Linear Te pirsa M andPin Connections a i T CIRCLE 725 ON FREE INFORMATION CARD Toshiba and Texas Instruments as well as Pro Electron numbered devices The author s selection was made based on his own experience of usefulness and practicality to hobbyist designers and service engineers etc A key is provided to show how to use the tables but it must be remembered that with some of the equivalents shown there may be slight differences between the types listed in the first column and those listed in the last five columns of the tables Those differences might be in dimensions in dissipations or in some other mechanical or electrical characteristic Therefore it is recommended that if the conditions und
57. handling 64K Modem s Item H 796 63646 00 at 19 each plus 4 each for shipping and handling C My check or money order is enclosed No delays in processing orders paid by check thanks to Telecheck Charge to my I MasterCard VISA Acct Nopa END LL PLEASE PRINT CLEARLY Name z Address City FER State s owe Ap Phone z ii n Sign here New Products Showcase Continued from page 7 sensitivity for highway travel or filtered sensitivity for urban travel A single three position switch permits selection of either audible or visual or combined alert when radar is detected The unit may be either visor or dash mounted A power cord supplied with the RD 9 can be used fer either positive or negative ground vehi cles Its suggested retail price is 269 00 The other unit the RD 35 also features E D LT circuitry and like the RD 9 i5 protected by a 12 month warranty The RD 35 is lightweight compact and offers state of the art features and quality Be cause of technology efficiencies inhereni in its design it is priced at only 139 95 The RD 35 may be either dash or visor mounted and warns the operator by soun and a red warning light when X and K band police radar signals are detected Its E D I T superheterodyne circuitry is de signed to virtually eliminate false alarm sources such as nearby microwave relay stations radar do
58. higher losses and is commonly available in two popular impedance values 50 and 72 ohm It is reasonably flexible and relatively easy to install For most of our discussion we will assume the use of coaxial cable although most of the points would be just as valid for open wire lines Characteristic Impedance Undoubtedly the most important single characteristic of a coaxial cable for the beginner to understand is its charac teristic impedance typically 50 or 72 ohm That is not an easy concept to grasp and the beginner may have to content himself with accepting some basic statements at their face value at least initially Coaxial cable consists of two conductors one within the other and insulated from each other A common form uses solid or stranded wire as the central conductor copper braid as the outer conductor and a polythene insulating material between them The characteristic impedance is a factor of the inductance of the two conductors relative to the capacitance between them per unit length Those factors in turn are determined by the physical characteristics of the components the induc tance by the cross sectional area of the conductors and the capacitance by their area relative to each other the distance between them and the dielectric constant of the insulating material The length of the line is not a factor The effect of that inductance capacitance relationship i5 to establish an equally firm relationship bet
59. in 1978 and has published numerous articles in such popular magazines as Microcomputing Sync Timex Sinclair User Radio Electronics and Run Magazine Scott Foresman and Company 1900 East Lake Avenue Glenview IL 60025 Paperback 228 pages 12 95 Saxon on Scanners Continued from page 17 to us for help and we in turn looked up the wanted frequencies in several refer ence guides in our own library Rail Scan and Air Scan The Texas State Railroad Commission operates on 39 94 MHz NASA in El Paso is on 121 75 MHz Long ago we realized that some of the frequency directories of fered by chain stores were satisfactory for beginners and those with a very casual or passing interest in scanners but those ref erences were a waste of time and money for hobbyists pursuing scanner use On a serious level For directories oriented more towards the serious scanner user request a free catalog from CRB Research P O Box 56 GP Commack NY 11725 They publish the Rail Scan and Air Scan directories mentioned above and also offer many other books and guides for scanner and shortwave enthusiasts Tune you in next time around e Look at the world as it was 20 years ago and as it is today Now try to name another field that s grown faster in those 20 years than electron ics Everywhere you look you ll find electronics in action In industry aerospace business medicine science government communications
60. including Sony In brief the test function scans for shorts the run function permits you to observe any open circuits via the symptoms that ap pear in the CRT screen HOOK UP Simply remove the set s horiz output device and replace it with the scanner s interface plug No wires to disconnect no other connections required not even a ground connection MISTAKE PROOF No damage will result if an error is made during hook up The scanner simply won t turn on until the error is corrected PUSH THE TEST BUTTON Just one of the four lights will lite JUST ONE BUTTON RED OPEN LIGHT means the emitter circuit of the horiz output stage is open no ground path YELLOW SHORT LIGHT means the flyback primary HV multiplier vertical output horiz driver and R B G color output stages are not shorted Instead a circuit that normally draws a small amount of cur rent is shorted i e the tuner IF AGC video chroma matrix vertical or horiz oscillator RED SHORT LIGHT means either the flyback the HV multiplier the vertical output horiz driver or one of the R B G output transistors s shorted GREEN NORMAL LIGHT means the TV set s entire flyback circuit s totally free of shorts It also means that it is safe to power up the TV set with the run button so that you can look for open circuits by observ ing the symptoms on the CRT screen FEATURES All start up circuits and all horiz drive related shut down cir
61. input of the next flip flop in series Connecting flip flops in a chain like that is referred to as cascading The input pulses to be counted are applied to the toggle input of the A flip flop All J and K inputs are assumed to be at binary high Another important connection shown in Fig 1 is that all of the clear C or reset inputs to the JK flip flops are connected together That forms a clear or reset line A binary 0 applied to the line will reset the flip flops so that the binary number stored in the counter is zero 0000 You observe the binary number stored in the counter by looking at the logic states of the normal flip flop outputs You read them from right to left or DCBA If all the flip flops are reset the normal outputs will all be binary 0 The A bit is the LSB least significant bit and the D bit is the MSB most significant bit Now let s see how the counter operates Assume that we are using JK flip flops that toggle or change state when the clock or T input switches from high to low or from binary 1 to binary 0 We call that the trailing edge or the negative going transition of the input pulse Now assume that an input pulse occurs and it switches from high to low That causes the A flip flop to toggle switching from the binary O to state Looking at the flip flop outputs and reading them in the DCBA order we see that the binary number stored in the counter is 0001 Naturally that is the binary reading for the deci
62. input pulse occurs The eighth input pulse changes the state of the A flip flop which in turn changes the state of the B flip flop and then the C flip flop The output change of the A flip flop also sets the D flip flop The code now in the counter is 1000 The complement output of the D flip flop is now binary 0 INPUT A B C D C B A 0 0 0 o Fig 10 Decimal to 1 o 0 1 binary coded decimal Albim 2 0 1 o BCD equivalents 3 0 1 1 4 1 0 0 B 0 0 1 1 0 0 1 1 0 0 0 gt y A Fig 12 BCD counter s input f 1 1 1 and output C ooo 9 oft d 0 ile o waveforms 9 0 0 1 It is fed back to the J input of the B flip flop That signal will keep flip flop B from setting the next time it receives a trailing edge pulse from flip flop A When the 9th input pulse occurs the A flip flop becomes set The code is now 1001 the maximum count capability of the BCD counter Flip flops B and C are reset at that time so that the output of the AND gate is binary 0 That makes the J input of the D flip flop zero The J and K inputs are now such that when the A flip flop toggles again it will cause the D flip flop to reset When the 10th input pulse occurs the A and D flip flops both reset The feedback from the complement output of the D flip flop prevents the B flip flop from setting Therefore the counter cycles back to its original state of 0000 Follow ing that description you may want to trace through the circuit yourself using th
63. is clearly safe to do so Most standard TTL gates draw between 2 to 4 mA Thus a quad NAND or NOR would draw 12 to 15 mA In the case at hand there was no current flow at all DTL or TTL would have shown some current so again the evidence sug gests RTL A third clue If there is a normal current flow raise the voltage to 5 volts measure and record l in the space provided at the right of the IC signature chart Step 4 Remove the milliammeter and apply the selected voltage directly between the V and ground pins Measure volts to ground mA to V_ through a 330 ohm resistor and mA to ground for each pin of the IC Record the measured values in the rows at the bottom of the signature chart The volts to ground row generally identifies all inputs and outputs Voltages from about 2 2 volts up to the applied voltage indicate outputs in the high state for a logic chip Thus pins 3 5 8 and 14 are likely candidates for output terminals You will recall in Step 2 that those are the same terminals that were suggested as outputs by their low readings in Row 4 A voltage less than 0 2 but greater than zero usually indicates logic outputs in the low state None of those appear RE 2 Now is the time to remove and reapply power to the IC Do that several times each time comparing the voltage at each suspected output to its original recorded value Often a flip flop will reveal itself by changing the state of one or more of
64. its outputs A simple gate will never change state in response to that little trick The IC in Fig 2 did not change state so assumed it was not a flip flop Voltages from about 1 8 down to 0 8 usually diete TIG or DTL inputs The fact that there are no such voltages in the volts to ground row of Fig 2 was certainly a surprise to me but it did lead to a pretty solid conclusion If the IC is not f t 3h DAL UN See FR Fat S MOS Se ene W f ONCE E m defective then it is not TTL or DTL Currents in the low state should read 10 to 20 mA when measured between the output and V Currents in the high state can read anywhere from 2 to 30 mA when measured between the output and ground if the IC is TTL As an example of typical TTL signature Fig 3 shows the signature chart for a 7400 TTL quad 2 input NAND IC Input currents for RTL DTL and TTL fall between 0 8 mA and 2 0 mA In Fig 2 all the probable inputs draw 1 4 mA referenced to V and nothing referenced to ground That verifies that they are inputs and shows they are active draw current when the input is pulled high RTL is active high DTL and TTL are active low Since there appear to be twice as many inputs as outputs the chart suggest that our IC is a quad gate of some sort It is reasonable to conclude that pins 1 2 6 7 9 10 12 and 13 are inputs The bottom row of the chart shows that the outputs provide only mA to ground despite the fact
65. leave it as is or just have the LED s showing The second method certainly protects the components but is much more involved It normally means going through a process called potting in which the components are set in a clear or translucent liquid that turns hard after a time Normally a mold is used to form a desired shape When the mold is removed the potting compound has taken the shape of the mold If the potting compound sets 9861 ga3d NVn e ai HANDS ON ELECTRONICS on a Fig 6 Details for making an on board power supply for use in electronic jewelry is shown Three additional boards of the same shape and size etched as shown are required clear all the components can be seen in side It normally sets as clear as glass Other compounds set with a haze so all that can be seen coming from them is the glow of the LED s Sometimes the whole board seems to glow if the LED s are set far enough down in the compound The compound is non conductive so once it sets there are no problems with short circuits Potting compound is avail able from most hobby shops Simply ex plain what you want to do and you should get the right material As for a mold various things can be used bottle tops paper cups etc or you can even make your own mold from plaster of paris if you want to achieve some unusual shape When potting you must be careful that the potting material does not ooze down into t
66. maining terminai pairs show 2rossly different resistance mea surements in opposite directions indicating the presence of one or possibly several semiconductor junctions in the path It is highly unlikely that a TTL IC or ior that matter any linear IC would contain 6 identically valued terminal to terminal resistances Maybe the IC is RTL or DTL Step 2 Disregard all circled boxes and scan the signature to locate the row with the lowest resistance readings Row 4 in this case That chasacteristic uniquely identifies pin 4 as the substrate connection of the IC or n other words the most negative terminal of the IC Scan across Row 4 for the lowest uncircled reading in this case it is the 750 ohm reading in Column 11 That distinctive reading tells us that pin 11 is the V e terminal of the IC Record those numbers in the place provided at the right of the chart Step 2 Fig 2 The other uncircled low resistance readings in the grcund row usually identify transistor collectors i e output termi nals That is an important clue to be used later Step 3 Before proceeding to the identification of other terminals we measure Apply a low voltage say 3 6 volts RTL supply voltage to the IC through a milliammeter or muiti meter preset te read in the 100 milliampere range The positive voltage goes to the V terminal in this case pin i1 and the return connects to the IC substrate in this case pin 4 To Protect the IC and the equi
67. of Emergency Communication They knew it was no accident because the intruder was using rather salty lan guage not normally encountered on the air Furthermore he was identifying his jamming station as Radio Free Portland Luckily the prankster s antics took place during a usually quiet period for the victimized agency no critical calls were delayed or lost because of the jamming A tip of the Hands on hat to Junior Bellomy and a knock in the noggin to any and all connected with the operation of Radio Free Portland may their antenna shrivel and truly wither Handy Hand Held Regency Electronics notes that their HX 750 scanner is a 6 channel hand held ON SCANNERS About cops Portland MARS tow trucks trains and other scanner topics By Mark Saxon MHz 118 to 136 MHz 146 to 174 MHz and 450 to 512 MHz Individual channel wanted channels LED s indicate which channel is being monitored The HX 750 comes with an AC adapter charger a ruesed flexible rub berized antenna and a speaker is provided but phone CIRCLE 742 ON FREE INFORMATION CARD Operation is by means of four AA bat teries it can also run from its external 6 volts DC plug in power pack The HX 750 uses plug in crystals that s why at a suggested list price of only 159 95 Regency can offer so much for such a reasonable tab A keyboard pro grammable receiver offering less frequen cy coverage than the HX 750 would
68. pulse occurs one is added to the count It is also possible to construct a down counter so that the binary number in the counter is decremented by one as each input pulse occurs As a result down counters count back ward For example if a 4 bit binary down counter were preset A LSB B n D Q Fig 6 Count sequence of a 4 bit down counter sa oO 0 1 2 3 4 5 6 T 8 Oooo a 200 002 2 2 0 O O a 8 O a O00 00 W O O O 0 0 O 0 0p O O00 O00 O SHIFT CLOCK to 1111 sequential input pulses would decrement it to 1110 1101 1100 etc Some digital applications require just such capability Figure 5 shows how to connect four JK flip flops to form a down counter Again the flip flops are cascaded by con necting the output of one flip flop to the clock T input of the next in series The main difference here is that we connect the complement output of each flip flop to the clock T input of the next However we still monitor the normal flip flop outputs to determine the count stored there With that ar rangement the count sequence shown in Fig 6 is obtained The table shows the counter starting with the maximum count stored in the flip flops 1111 When the counter is decre mented to zero the next input pulse will simply recycle the counter back to its maximum count value of 1111 The cycle then repeats That down count and recycling process is illustrate
69. so that it would be easily accessible when I needed it My first unit was placed on the night stand next to my bed I could easily turn indoor or outdoor lights on if 1 heard any noises in the middle of the night Later I decided to expand my system and control my stereo receiver a great idea if you re in the bedroom when you want to turn the stereo on or off I happen to live in a Dutch Colonial house with the stereo receiver located in my studio which is located on a different floor at the opposite end What I needed was a control system that would allow me the same capability as the BSR Command Console but conveniently accessible without purchasing more control units Besides my wife thinks computer oriented equipment belongs in the cellar or in a computer room not a part of the house decor Well what I decided was that since most families have two to three telephones in their homes why not use them to their fullest potential Let each telephone be a control unit and as you add more phones to your home you would automatically add a control unit at no additional cost Also with the advent of cordless telephones you would be getting wireless re mote control of lights and appliances here again at no addi tional expense Imagine what all that would cost you if you purchased these items separately in the marketplace Well figured that if I were going this far I might as well provide a built in security feature that would automa
70. system tester you can quicaly weed out your Taalty digital Ks a AP C T LL REI MEE LE EU Ee nr EIS iHay Comer Mew idea Se sice Clinic Equipmeat Reports Radio Electronics covers all aspects oi the fast moving electronics field featuring COMPUTERS e VIDEO STEREO TECHNOLOGY e SERVICE COMMUNICATIONS e PROJECTS e HOW YOU AND THE COMP amp TER CAN BE FRIENDS Getting Started Programs Circuit Design Games A D D A Interfacing Peripheral Equipment FOR YOUR PLEASURE Noise Reduction Devices How to Connect that Extra Add On Hi Fi Accessories New Technology TV WONDERS FOR YOUR FUTURE Latest Receivers and Circuits The Home Entertainment Center Projection TV Satellite TV Receivers Jack Darrs Monthly Service Clinic Service Problems and Solutions NEW AUDIO DIMENSIONS e REGULAR MONTHLY FEATURES DESIGNERS NOTEBOOK by Robert Grossblatt HOBBY CORNER by Doc Savage KASDS STATE OF SOLID STATE by Bob Scott WHAT S NEWS new products stereo news VIDEOGAMES new products game reviews and NEW IDEAS STEREO PRODUCTS NEW COMPUTER PRODUCTS FOR HOME JOB and MUCH MORE 1 Subscribe today to Radio Electronics Don t miss a single l issue and see subscription card in back of this issue for big savings When you select one of the subscription offers listed on the handy coupon you ll be assured of having your copy reserved even if it sells out on the newsstand Make sure you
71. the compo nents all except C4 a 100 uF unit common to both circuits and located at the center dividing line of the board are multiplied by two In other words two Ul s two U2 s and so PLAY A piece of red plastic about inch thick covers the PC board Holes are drilled to align with the pushbuttons and white lettering added TABLE 1 CRIBBAGE SCORING COMBINATIONS AND TERMS Card Values JN aua a ee ee ee ee Ace 1 2 3 4 5 6 7 8 9 10 10 10 10 Scoring Combinations uo Ww 3 Pair l Two cards of the same rank Pair Royal Three cards of the same rank Double Pair Four cards of the same rank Royal Three or more cards in sequence Three or more cards of the same Suit Any two or more cards totaling 15 i e 5 Q 7 8 A 8 6 etc To non dealer in five card game only To dealer only if Jack is turned up For holding Jack of the same suit as the starting card For playing last card toward 31 If exactly 31 Run Flush Fifteen ut For Last 3 His Heels His Nob Go on When populating the board do one side then flip the board around and do the other Start construction by mounting and soldering all the re sistors Clip off the excess resistor leads but do not throw them away Those short lengths of leads provide an adequate supply of wire jumpers Next make all the jumper connec tions some of them those i
72. the rounded peaks of the signal to produce a squarewave suitable for driving the dividers that follow That squarewave signal is sent to U20 and U21 where It s divided by 60 U20 is set up to divide by ten and U21 to divide by six resulting in a frequency of one cycle per second at the output of U21 That point is tapped off and fed to three switches on the rear panel and routed to the inputs of U4 US and U6 More on that later The output of U21 is also fed to U22 and U23 where it is farther divided so that a signal frequency of one pulse per DIS2 10 S OF MINUTES 1 6 4049 1 6 4049 uj S15 Fig 2 Complete schematic excluding the power supply of the Before and After Clock Clocking for the circuit is provided via a resistive network made up of R36 and R37 located in the power supply circuit The circuit s almost completely integrated circuit construction makes it a snap to build using the foil patterns provided Note that the numerical sequence of the resistors and capacitors has been broken by the exclusion of R27 R29 R31 R33 and C2 from the final layout 4 i MET minute is now arriving at the input of U4 pin 15 Up down counter U4 sends timing information to Ul a seven segment display decoder driver which then lights the display DISI to shcw the minutes count The pin 4 output of U4 is fed to the input of U5 at pin 15 where the signal is divided still farther and used to fee
73. the waveform is determined by the sLopk control Normal mode triggering is used when proper triggering can not be obtained using the automatic mode That could occur with complex input waveforms or waveforms that are near the upper and lower frequency limits of the scope It is also used when triggering at a specific point other than the O volt crossing point is desired Using a Dual Trace Scope Dual trace scopes can operate in either the alternate or chopped mode In some scopes the selection of the display signals are time related use the channel with the lower frequency signal as the triggering source mode is automatic but in others the decision is left to the operator Which display mode is best to use will of course vary with the time base selected and with the scope As a general rule of thumb however use the chopped mode at time base lengths of less than millisecond and the alternate mode at millisecond and faster Usually dual trace scopes can be triggered from either channel or channel 2 If the inputs to the two channels are time related have the same phase but are of different fre quencies the channel with the lower frequency signal should be used for triggering For example Fig 2 shows a dual trace display The upper trace is the clock signal being input to a BCD counter The lower trace is the output of that device There triggering would be selected to be on the trailing edge of the lower wavefor
74. this layout you should have no problem installing the components in the right positions with the proper po larization nent to be placed and soldered to the board It is done last to reduce the risk of thermal damage Insert the integrated cir cuit into the holes on the board until the little shoulders on the pins prevent it from going any farther and make sure it s cor rectly oriented by noting that pin marked with a circular indentation is connected to the ground trace on the board Then turn the board over and care fully solder each of the pins to the pads making sure that you don t run solder between the pads Inspect the connections to make sure you ve soldered them all without shorting out any of the pads and that s it Solder on the battery snap wires to the points indicated in Fig 3 taking care to see that they have the correct polarity red positive to the pad marked and black to the negative pad marked Before you connect the battery check again to be certain that all the components are in the right place correctly oriented and soldered properly Clip off any excess wire or lead Connect the battery and test the circuit by bridging the key switch pads That should cause the relay to operate as the normally closed NC contacts would still be open We haven t connected them yet The relay will stay activated for about 986 B3d3 NVf o e alkaline powercell
75. ts purpose is to reduce the amount of current consumed by the device and to isolate the logic gate inputs The input voltage passed through the resistors drives the output stage into saturation making the collec tor voltage of the output transistor drop and causing the output to go low The resistors though slow down the switching speed output appears on pin 3 That procedure is continued until all inputs and outputs are related in some way Truth tables can be consulted to identify the gates The device turned out to be a quad 2 input NOR gate The relationships between the inputs and outputs and the conclusion as to the type of device I was dealing with are listed in Fig 2 as Step 6 Had the device not responded at all to any of the above INPUTS o Vcc ied IN AE sch INPUT PROTECTIVE DIODES bir rr niin INPUT PROTECTIVE DIODES SUBSTRATE DIODE DUTPUT l SUBSTRATE DIODE OUTPUTS SUBSTRATE of RTL devices because they increase the time needed to charge and discharge the input capacitance of the output transistor Typically RTL has a switching speed on the order of 50 nanoseconds and operates at a 3 6 volt supply The next phase in IC evolution was DTL That family substitutes diodes for the resistors used in RTL The di odes provide better isolation at the inputs and because of their low forward resistance make it possible for DTL circuits to switch more rapidly than their RTL equivalents DTL
76. two LED3 RED LED2 YELLOW LED YELLOW Fig 3 The recommended layout of the indicator LED s but if necessary they may be arranged in any way that s convenient for you Just be sure to observe the proper polarity when connecting them to the board PP regulators are shown in Fig 2 The two 15 volt regulators require at least two 17 volt inputs for proper operation Since the Indicator has been designed for use with the most common 15 volt output type of power supply that voltage should be available at the supply s unregulated portion If the power supply output is less than 17 volts the unregulated voltage probably will be lower too If that s the case lower output regulators may be used in place of the 15 volt units Most IC regulators require an input voltage of 1 5 2 volts greater than their rated output With higher power supply output levels up to about 30 volts the 15 volt regulators may still be used but the Indica tor should not be used with power supplies that have more than 25 volt outputs to prevent damage to the LM339N integrated circuit Other than the voltage requirements the only portion of the Indicator that is critical are the two divider strings The four 100 000 ohm resistors R4 R6 R7 R9 are the backbone of the dividers and should have a tolerance of 1 or better Resistors R4 and R6 are particularly critical because imbalance between those two units would result in an er roneous bala
77. us Toll Free 1 800 328 0609 PRINT METHOD Bi directional impact dot matrix CHARACTER MATRIX 6 x 7 dot matrix CHARACTERS Upper and lower case letters numerals and symbols All PET graphic characters GRAPHICS 7 vertical dots maximum 480 col umns Dot addressable CHARACTER CODES CBM ASCII code PRINT SPEED 60 characters per second MAXIMUM COLUMNS 80 columns CHARACTER SPACING 10 per inch FCC Approved CP Factory gt New MUST LIQUIDATE AT FAR BELOW DEALER COST Computer Products PUBLIC NOTICE We are authorized liquidators of consumer products that must be quickly sold by manufacturers at drastic price reductions for many reasons such as Discontinued lines Last year s models Distributor surplus Can celled orders Out of season products Tailends of inventories Whatever the reason for the liq uidation you are assured of fine quality at money saving low prices Supplies are limited Order now LINE FEED SPACING 6 lines per inch in character mode or 8 lines per inch selectable 9 lines inch in graphic mode LINE FEED SPEED 5 iines per second in charac ter mode 7 5 lines per second in graphics mode PAPERFEED Friction feed Tractor feed is option al Available from dealers nationwide PAPER WIDTH 4 to 8 width Up to 10 with optional tractor feed MULTIPLE COPIES Original plus two SIZE 13 W x 8 D x 3 4 H WEIGHT 872 Ibs Mfr List
78. we complete the global junket by turning our eyes make that ears toward Latin America Shortwave listeners like other nor teamericanos tend to think of Latin America as being right next door But like many other of our perceptions of the world that is only partly correct Certainly Mexico Cuba and the Cen tral American nations are our southern neighbors But Latin America also in cludes countries such as Argentina Bra zil and Chile tar more distant than we may realize New York for instance is closer to Moscow than it is to Rio de Janeiro From San Francisco it s about 5 000 miles to Tokyo but nearly 6 000 to Santiago Chile A beeline from Chicago to Istanbul is shorter than one between the Windy City and Buenos Aires In the common stereotype a Latin country is purely Spanish in language and flavor But in fact Brazil the largest South American country is Portuguese speaking and in French Guiana Guyana and Surinam French English and ces m E E ua T A y a Dutch respectively are the predominant tongues Many native born citizens of the southern tier of South American countries have German Italian even Japanese as their first language Additionally there are many who speak the various Indian and Creole languages SWL s soon find that there is no singl type of music typical of Latin America The Argentine rango the Colombiar cumbia the Mexican Mariachi the Peru vian
79. will reach into places others won t Cat T 3570 Solder Stand with Magnifier The heiping hand when yu need it most when you have a hot stick 6 in your hand Heavy die cast base yE ey solder stand clips for holding PCB etc plus a unique m iens a2 VE 1 DER EVERYTHING FOR THE bipes ENTHUSIAST Cat T 5710 u STORES AT BERKELEY 2474 Shattuck Ave Ph 415 486 0755 REDWOOD CITY 390 Convention Way Ph 415 368 8844 T s SAN JOSE 4980 Stevens Creek Blvd Ph 408 244 2266 f STORE HOURS San Jose amp Berkeley 10 AM 6PM EVERYDAY d ELECTRONICS Redwood City 10AM 6PM Mon Sat 12 5PM Sunday LJ MAIL ORDERS PO Box 8021 Redwood City CA 94063 5 HEAD OFFICE 390 Convention Way d INCORPORATED IN THE STATE OF CALIFORNIA EA D o 0 00 0 an Z NEARLY 70 STORES 33s TA apa IN THREE COUNTRIES io JV SU qn or one J HORDER TOLL FREE 1 800 332 537 CIRCLE 717 ON FREE INFORMATION CARD 7 Negative lon Generator You ve heard all about N their benefits now buy the kit and find out what it s all about Many commercial units run from the mains but our kit is safe it runs on 12V DC which also means that you can put one in your car Kit includes exclusive Dick Smith emitter head power pack and tough moulded plastic case Cat K 3335 xr and Q A continuous current It s priced at SiS For more information write to Test Probes Inc P O Box 2113
80. wired telephone to determine which pair is used TABLE 5 CABLE COLOR CODE A 4 Conductor Cable 6 Conductor Cable Blue with White Band White with Blue Band Orange with White Band White with Orange Band Spare Wires Green with White Band White with Green Band 5 Insert the Control System s modular phone plug la belled INPUT into the modular phone Jack which is now connected to the protected intertace 6 Insert the Control System s modular phone plug la belled OUTPUT into the modular phone jack connected to inside house wiring PARTS LIST FOR TELEPHONE SEMICONDUCTORS D1 D2 D3 D6 1N4148 silicon switching diode D4 D5 1N4001 rectifying diode Q1 Q2 2N2222A silicon NPN transistor U1 8035 6 microprocessor National integrated cir cuit U2 74L8S373 8 bit latch integrated circuit U3 2716 EPROM integrated circuit U4 ULN2003A hex Darlington NPN transistor array driver Sprague integrated circuit U5 LM341P 5 5 volt regulator integrated circuit U6 4N33 opto isolator integrated circuit RESISTORS All resistors are Ya watt 5 units unless otherwise noted R1 1000 ohm R2 200 ohm R3 R5 100 ohm R6 R14 R16 10 000 ohm R7 R8 R10 4700 ohm R9 510 ohm R11 R15 430 ohm watt R12 R13 51 ohm watt CAPACITORS Ci 2200 pF 10 WVDC electrolytic C2 47 uF 6 WVDC electrolytic C3 47 uF 250 WVDC C4 C5 047 4F benamic cisc 117VAC 7
81. wish I had it would have saved a lot of time The Motorola book had 256 pages of RTL data whew Fortunately the plastic case style of my IC eliminated two of the three RTL sections The index of the remaining section listed only two IC s that were quad 2 input Nor gates The collector pull up resistors of the first IC type were nominally 640 ohms The collector resistors in the second IC type were nominally 3600 ohms Bingo We measured 3500 ohms in Step 4 not bad The device is without a doubt an MC717P 817P and all the information on that data sheet applies to this IC I am unable to differentiate further between the 717P and its higher performance counterpart the 817P Since the safer move is to assume that the more restricted temperature range applies declared the device placed under inspection to be a Motorola RTL IC type MC717P Continued on page 101 Fig 4 Five typical logic input and output circuits are presented here Use these circuits along with your resistance measurements to determine the logic family of the unknown IC WHAT IT MEANS IN PRACTICE When amateurs get together and the talk turns to antennas it is not long before the magic phrase SWR is heard Just what is SWR and how important is it in practice By Philip Watson VK2ZPW IS AN UNFORTUNATE FACT THAT SWR ALONG WITH antenna and transmission line theory in general is one of the most misunderstood subjects in the whole of amateur radio
82. 00 d B 2 DEB ws Z 66 ij bec MLSTEN 83 TDAWPA 6 eoe appe 335 No Ovecription Pkg 3 10 100 1000 oes 3 09 1301110 253 125 070 8 3 lun jf LM339 85 B1 N icrgprocesso 30 D 16 85 RS306 seach of values 4 100 181 1586 128 178 1525 FLSI N V Dawgs Hgh Performance B Bit z IN5400 3 Amp SOPIV Plast 28 256 2280 19950 ieee EA es f i ioo 316 2209 252 325 17 4 feas UEM S M Seo 21 Lee Do aos NB 3 Amp Mov Piste 30 270 2400 2 000 fp eri Musisgh 7 MESESN dE rr eee TAR rw a eet aa aad ense s capacitors ee k NESS N ate n us Pias ap Z3 m 7ASISSN 88 NESEN Microprocessor 40 Dip 33s V9406 2 Amp SO0PIV Pasw 35 315 2800 245 00 10 Weni Resistor Assortment ASSORTMENT OF 18 ius 7ALS1 27008 8 Br CN OS 1N5407 3 4 V oP 1 L5156N 100 JAT23N JM enm er NES Amp RCE P s 40 360 3200 2800D f ATIO 2oanh OL at SPON vales uss POPULAR amr pres c J BAGR 3 Ame 1000PIM Ptasie amp 168 10tai pcs CAPACITORS 3995 P4536 P4537 The Digi Key volume discount and service char dc SCO ges are simple to apply Most items sold by Digi Key may be b t ND tot i y combined tor a volume Ount hems that ai chat Wer MT diei After writing your order total ail of the discountabie items and apply the appropriate discount To this subtotal add the guisa tiii jc eb me ao charge Doing insurance to addresses in the U S A Canada and Mexico when check or money order accompanies order Digi Key only ships SE NT p hy des pred withi
83. 00 TAHCTI3N 935 juive sgj prezan 833 cm2 20e Ma e pe te aL GEN m Ed ud E 28 255 2135 19125 TAN 63 74HC123N 270 z es duced 74 00 2 f 31 270 2250 20250 LM587CN 1 93 OPS303N 500 CR 27 pin wira wrap t 310 DISC P2055 027 4 J 74123N BO 74MC 25N 205 36 DPRIO4BN 467 as P wren tn 83 820 Hl00 A lt arz 35 3 2 25 X250 7A125N 7 1 Bo L M709CN 96 C8124 Won wire wrap un 91 q d CAPACI P205 033 5 3 7m 225 co es oe 180 M723CN BAPOPBIOIN 500 cae 28pm wewn in s BOE Lao b APEC ORS Phe 0H Bo n rx 29 Ww 74132N 83 J4MC 123N tease 4 95i DPBGOBN 5 00 pi wire weap un 4 1030 0 0 tL D P2055 48 J n L 2 50 dala 1 JAHCI3BN 135 plu Selon amr ose nn DAR ae Mirco tm alors P2059 35 220 25 55 Ms 19 on Bias Me Be Ko ar 0 0 0n w EIES i IMMDCN 119 asi Wo Doseription 1 i Rated Ambani Tem 7PC P2D62 3 pin T a MEE POE 10 iMDBEN Ed INGBRBSN piso pun wire wrap uona 5 5 h E Dico TATE um ec is PAS 1 3 Feed ed nr LM1310N 116 C9114 1A pre ware ote 5 PA 68 35 ry 3 IBIN 73 74AMC SAN 350 200 saw 774 NS8OIBN 179 80 canis Bier wanes CI EOM 70 m 878 5650 50830 7 C9116 pnwrawrap gold 8 n Dimension L fib P2065 t4 35 1 900 7500 6 500 DIN E SAMCISUN E i x RM IADGN 65 INSEDGON 18 75 C8118 TB om wits wrap o yu E E b Dimension D 23 b3 18 154 28 P2066 1S 35 238 2040 17000 153000 3154N 50 13 CMIBOON 1 gaf S8073M 100 00 fCS120 20 pin wre wrp gaid 1 1 E 63 20 188 04 1s 112 i19
84. 1N4001 2 T2 ONE OF 3 WINDINGS 1 N 5V R1 1K 1 7 ULN2003A R5 10082 Fig 1 Power supply and RF oscillator circuit combine to produce the voltages and signals necessary to operate the Control System s circuitry Two diodes D4 and D5 form a fullwave rectifier circuit A signal picked off the anodes of D2 and D3 is fed to the base of Q1 located on the control circuit board to form the zero cross detector control modules all at one time i e ALL LIGHTS ON The first consists of transmitting a sync identifier followed by the house code then the unit number waiting 50 milliseconds then transmitting another sync identifier followed by the house code and then the command code The whole process takes about 416 milliseconds The second operation consists of transmitting a sync identifier followed by the house code then the command code then the cycle is repeated again That transmission takes about 366 milliseconds Table 3 lists the house codes and Table 4 lists the unit numbers and command codes that will work for the Tele phone Remote Control system The sync identifier is required at the beginning of each transmission and consists of the bit pattern 1110 In all cases a one is transmitted as 3 bursts of 120 kHz lasting 1 millisec in duration and separated by 1 6 millisec All that takes place in 4 AC cycle 8 3 millisec A zero is trans mitted as no burst of 120 kHz in a AC cycle
85. 29 1 24 3 z 32 288 2218 20038 748253N M317k 5 09 7806 90 MPH oe A Dimension D 5 91 27 34 2981 2425 2825 BE AMHCOEAON 3af 77 56 A700 30 OS 1488N 125 ee A s 52 A 45 55 a ch im 16 65 17 1Y38 50 E2334 20 V 3 35318 26 3 2387 745257N 1 74HCBASN 203 DS14B9AN 125 BM PS2222 3 2X tg 90 mension d z s 1953 21 173 44 E2394 asi lancen 23 297M hears Wf osisgn 125 MPS23694 E 15 x SG aa o A 8 5 nh AA NEUE m oco 4 30 oa OAE AN7812 30 gt x 20 yg St 5 Mats Oude Film Vatues in Ohm 47 220 m 2 a3 358 3065 27585 23 amp 744C400N c8 M3177 193 anyes aq ff 724508 90 952207 23 220 R 90 AIM 1 a3 375 3124 30 342 2845 E2564 250 56 47 402 V 30106 741800 TTI 4 3f ecan c75 M 8N 88 faneg go 2SN 38 MPS3395 7 20 200 How To Order Take any standard value ie 1 SK and 39 2s 3 ia aiza 5 58 aol im x 8 ck in 203 115 M3 EE watt or add a b E d 51 Pan ER 265 74HCADAON t75 vcl T 5 AN7R20 904 75452N gg E MP 53562 78 S2 2290 ae pes S a UR i i d 7 8 7a sgae 83 706 58 us EZ 280 82 A iM a4 371 MON Ju 2 apy arcae cn S72 1S ANTE 99 754535 ga MPS3565 23 20 89 number cadi a 2X0 25 106 99 amp amp 117 O02 8147 EE AO E T gee Mie 74 S01N 50 3 TAHCAUGKON 135 LMOBOSCK 3030 75554N 88 MPS36384 73 220 18 amp Prie 3300 2 181 137 1147 166 417 11602 m 20 972 582 4850 436 50 74 502 Spass 3 THRTEHCAOGON 2037 MAPOLZ is 1 3B M7BIZcK 303 TAN 95 E MPS3641 23 220 mA eiie s a0 se 1 0 9 9 Um uS Em RE 4 49 55 AE Bip no n
86. 3 nfs 2 6 5 567 4725 12525 56 Pu bea sgia og VM21 7 17 50 f E8922 2 pin solae tal tin 25 225 100 5 Carbon Film Resstor Values n Ohms 10104 7m 203 180p 500 63 543 apres 3 8 58 585 4975 4H 5 88055 5197 E 525 mon 138 O3 M27160 738 86924 24 pur solder tail tr 78 250 0 How To 0 PADA 220 pf 500 p 5 43 40 72 P2017 7 8 621 5175 415575 38741 221N 135 s 75 08 E o3 ssa cms 28 puts solar tail S GH Schoen ete a cM x m Em QUE Pos MO 6 255 2189 18236 154026 74 38 E Ma rw 7 an or rewan ores t 4 wart 0 2 1 1 5 a 74652408 145 24c927 HE 1B 58 E ae CB940 40 pin sokhi tai t 4 320 3900 oan P forti2 ami 8 32010329 aan max Bene So 30D 83 8a ac fem 150 8 2 3223 9 ior te 5 B74 241N 45 0228 1 58 543 GOLO INLAY SOLOER TAIL s tha Digi Kay part number Paio 300 500 83 43 72 909 0 63 334 3720 37000 279000 53 hoa 5242N ag 74C928 875 f 26 a6 e 029 saeco hee Bata P3108 370 pt 500 80 B91 51 a5 8 27082 330 63 5B 1980 415 3 E rese mcm te 56 105 250 Beans o Pricing amp ma 1000 Je ssop am E2 00 373500 45 4 5243N JACBAIN 0248 1 08 106 31g sicnription 1 1D 100 lew p BO 69 53186 f 72227 10 31 270 2250 20250 53 40 9244N des 30258 50 105 20008 03908 8o sobter ral got 34 320 3000 i 235 G40 2500 Pato 68 pt 500 80 K91 186 52075 z us 31 270 22590 X250 58174LS247N 50 100 10276 68 3 82 12 88 9815 14 uin soht tail qoid 44 120 5 00 1 4 Watt 25 340 300 P4111 820 p 500 B
87. 339 BF 1026 56 R isb 5 NO RBS 10 ND R amp G 25 ND 522 88 4577 50 68556 6002 50 1184 20 10 197 00 Cas No MA 1020M MA 1020P Deacaption MA1020 Cloce Module oniy Digi Key sw tching Canal includes Price 18 55 7 95 X046 1 8432 X067 1 B432 x0Q1 2 000 HC 33 HC B HC 33 2118 2482 28 amp b 2 23555 314 2771 368 1252 310 40 351 3104 413 3651 23721 20840 1313 944 3930 17000 378 3330 212 1910 00 442 300 sB00 227500 9 3485 72213 igs ODM 4 458 3887 25270 726 COMI 36 4741 29857 267650 M14 287 4307 27219 244100814 56 4964 31218 779800 4 731 5950 37215 232350 R325 b Nn 574 5078 31912 286000 Big aD R325 18 ND amp b 5851 38616 203000 Big 4p R325 36 Nb 792 7010 43677 136720 16 40 R326 8 NO 658 5819 36470 3262 15 5 R325 18 4D 1B 6 A5 4230C LE 8326 26 ND azt 823 1120 45 50 g s 20 24 2300 7483 26 13 27 72 30891 23 00 24 3 26 13 2772 30 1 23 00 24 53 26 13 27 72 505 13 05 1487 1199 7 1350 C 1433 2 1519 Bf 1606 5C 1278 7 1350 0C 1433 25 1519 88 1608 50 1779 75 1350 X 1433 25 1519 88 1506 50 1779 7 809 30 908 00 1007 00 1146 24 1304 00 8318 B 40 6 A319 18 ND 2 R319 J ND 4 A320 6 ND 7 A320 18 NII R320 35 Ni A321 64D R321 18 NU 16 A321 386 ND 0 R122 5 MD 20 R32 38 ND 20 R32 38 ND 26 R323 5 ND 26 R323 18 NO 2E R323 36 4D 14 R124 B ND 14 R324 18 ND 34 R324 36 ND 40 142 44 158 21 1B4 44 158 3 17889 128 504
88. 362 50 55768 499000 710 56 8635500 1179 20 16 450 XI 2003 60 17 375 10 382 48 89000 1035 9255 00 1514 40 13380 00 2348 4 20 275 00 95248 B515 00 110536 5880 00 1614 00 2348 40 91748 8202 50 1070 36 95967 0 RE14 25 ND 1619 00 13 662 50 RF 4 8 Nn ZAR 4 20 3 amp 7 22 Pin D SobmiruaturelAssembhes R 7 5 ND 13 96 76180 6817 50 RE 10 NO 1833 101700 8912 56 REV 2b ND 3143 1772 60 15 412 5 REV XHND 5377 3038 60 26 312 50 HZJ amp NO 14 92 1360 2275 06 Rz7J0ND 1929 1048 BO 9375 00 AD 25 ND 3240 1 54 40 1567500 ATV 50 KNO 324 3030 40 26 27 58 R61 5 ND Z3 56 1278 40 114250 R61 10 NO 7232 1513 60 13 52500 R613 25ND 4103 2269 20 t9 B25 Di Rei 50 NE 6 87 3615 20 30 525 00 R711 5 ND 25 48 1382 00 12 350 00 ATI ION 2985 1617 20 14 450 00 R O11 2 ND 4235 2322 BO 20 750 00 RT1150 ND 64 9 3618 00 3 25000 H amp 15 5b ND 24 82 1330 20 11887 50 Rri 10 NO 2889 1565 40 1198 50 Rr15 25ND 4199 227 00 20 287 5 R15 5 NO 6383 3637 00 an x068 2 0000 MC 1B X002 2 097 C33 xoy 2 216304 HC 23 X027 Z 30 HC 31 x04 2 4576 He xDn6u 2 4576 x070 5000 MC x003 z566G HC x017 2 500 KOl 2 949120 x 8 2 95936 iux 3 45 3 2768 3 579545 3 579535 3 594686 1 540 3 b86 C 18 3 840 133 3 B58 4t 3 35312 33 40 1B a 0320 C 18 1 194304 8 PC board switches h rdwaim and nstructiona 30 VAT Transtoarmer for 4A 10208 Buzzer for MA1020M aiarm output MA1020M P BandT MA1023 0 7 INCH HIGH DIGITS D
89. 366 DIP Jumper Cable Assembly Standard Assembly Styles Sts 2 m Eog 56 38 8 31 96 i3 357 128 72 41114 487 29 596 99 701 32 99 60 3707 5 43t 1 0 5341D 6272 5i 7150 Of Fert Bo Wee p 1 LI C41 435 4226 Ca 15 20 4950 IB 53 30 220 5 0 C4 22 55 10 C4 25 6430 C4 28 65 70 CA X 67 70 c4 31 70 bO c4 35 80 60 24 38 amp 70 C 40 B 10 Caw 995 93859 C344 74 C450 103 10750 C350 790 EUM 4 H4 SER cS 156 x 2007 EDGEBOARD CONNECTORS Color Shape Red Oittuses ed Civar Grean Cigar Green Diffused Ambar Clear Orange Clear Amber Diffused Orange Diffused Red Ciegr i een Clear Amber Clear Red Cinar Green Clear Amber Drffused Hed Diftused Green Diflused Amber Diffused Red Ditused Grenn Urfused Amb Ditused Red Olfuses 140 175 Typical Applic ations Inckoda Zlocha Radio fimers Alarm Clock Stereo Instrument Parii nometer and much more Pert No MA1D26M MA 1026P TV ang Ther Round Round Round Raun Rounc Round Rounc Round Round Rounc Rounc Round Round Round Raciangia Rectangle Rectangie Arrow Aftovy Arrow Dor Sar Graph Desk Clock 609 20 Clock Ongrial 819 20 1250 20 5iB 20 588 20 5 50 Timer 5 90 6 20 6 60 6 70 6 90 730 8 30 835 8 30 395 120 Prica 30 6C 1195 Description MA 1026 Liock madue only Bayi Key switch panel kir Board 12 switches rwo temp senso two KOA3 bommar aysiructions 110 VAC rranstocmer lor MATOM
90. 40 311b D0 ya R102 6 ND 1227 BA 66 14 R102 12 ND 1386 S436 AGB 25 ND 185 38 1248 40 10 175 Q0 16 10 0 7 or 0 84 Red 4 Digit LED Display R amp S 50 ND 276 45 1892 BO 15 225 00 CT 12 User Programmebla For z s 1A R102 18 NO 1545 T0407 a505 36 ND 3k Sa m F102 24 ND 308 0937 ARS 5ND 12218 75358 8740 00 15 2 12 of Z pour display R71 10 ND 16039 86456 773000 CIS 50 amp Hr ne frequency A506 36 NO 156 403 25573 229 00 R50 36 ND 57 076 31895 125250 R102 36 ND 1606 13042 R104 6 ND 12 2 R75 25 ND 195 04 1187 20 10 706 00 Fed of Hashing dol Iroton ndicator R5DS 36 ND 15 5975 37322 31050 Port fo Wira Wreg 1 1 c6 io 385 3760 C6 15 1350 4340 C6 17 270 24580 Ce 18 60 uy C620 530 48930 C6 22 60 5350 C625 59 5790 C6 28 639 6140 26 30 540 6260 C6 31 670 570 C 8 35 B0 7630 C636 50 7380 C640 8B0 8410 C643 330 WN Ce49 1060 10460 cs 990 39830 H4 SERIES 125 x 250 EDGEBOARD CONNECTORS Pen No Sode lee 1 C310 2 C373 340 C18 C3 20 C3 22 326 C3 28 C3 30 C3 C3 3 C3 35 t3 46 P332 P333 P334 P335 P336 P337 P338 P339 SIROSBESRSESLER 204 46 223 28 254 6 2723 320 55 383 29 461 92 525 60 1836 75 205 paf E 2254 60 2447 60 2872 75 3522 24 4135 00 371740 a wh P357 P398 P353 P360 P340 P36t PHI 8362 Myttipres nd Display LED Time Temp Clock Module Giant 7 Inch 4Digtt LED Display Fand ot C and virtually any number af sansors 5 50H ina Ire
91. 5 Cat K 2621 Justas Volume 3 rando The logica progression rea tl dice for those who have work Cat K 2625 ed through Fun Way Vo 1 and 2 it s for the more advanced hobbyist because Fun Way Volume 3 projects are all based on integrated Circuits Cat B 2610 MY Electronic Siren what to do Cat K 2636 o E pot Flasher I Make it as the latestin elec tronic jewellery or a burglar warning light etc The choice is yours and it s easy 2 much fun using A is 4 nu ads puilding noche Just what you need with the alarm Also makes a great sound effects circuit and Fun Way 2 tells you 495 LL FREE 1 800 332 5373 A Blink May Be a Boo My baby has a small teddy bear and I d like to replace the eyes with a pair of alternately flashing LED s Have you got a schematic can use R T Fresno CA lt 4 Yes but first a brief word Childrer are usually afraid of the dark because they are unable to orient themselves A small night light kept in the same place all the time eliminates that fear Aiso when you add the LED eyes to that teddy bear don t be surprised if everybody else says its cute but the youngster suddenly becomes afraid of it That kind of thing has happened more than once For Better Hold Ups In your Summer edition 1985 page 74 the story Put Your Telephone on Ho
92. 5 315 az 366 3056 27506 007A Y 53 1n s S cwracosacz i22 e EE dye iio woo d SR Una CE GUESS a 6 E54 S170N ed Se peret 158 e C M SL 12 C2 1 38 gokt sockets Wettaga Rating SW bow 12W P4005 27p 500 P4 8 49 481 P2006 a 45 0 4 00 5 TAESTIINO Ue 3 18 actua Fi 33 Voies oco ddr ari Max er ng oes 200v 250v 350v ES ot 500 75 6 49 46719 P2007 56 1 5 m 575 5625 50625 Fol zasi E 13 38 f 40118 59 38 E Raled Ambani Temp Z C PAQ 9 of 500 75 6 aS 675 2008 100 315 97 B3 6975 62 78 L N Bo 13 o0 4o 38 Part Wa Dagcription 1 10 100 Panga x pl 500 75 549 480 P2008 150 315 27 1950 16250 145250 74LS175N B x 128 50 CaA s Operating Temp Range BEPC Plon 220 gt Sousi oN 113 13 00 Tu 23 CAA 8 bir sown ta 13 11b 1050 col te Un UNA a to 156 C PAXS 56 of 500 75 5 49 sni 315 71 2355 19625 176525 sep d 40138 63 65 Cagis 14 gon solder tai nin i5 145 12 00 Dimension L 390 650 P4010 pf S00 84 23 2422 P2011 47 B 3 270 2250 20250 44 1915 113 2 50 f wise 155 9 50 P2017 68 5 60 be M A2114N C8315 ti solder tail lin y 1 1 P4011 82 pf 500 37 321 2681 21 MLSI92N 108 200l so 8t 60 3 00 4 pi 84 23 5422 r 68 30158 140 C Dimension D 150 230 320 2013 10 amp 5 a29 358 salas 13 00 f so168 65 Dep AMZ MNS 3083 CASTS AG pr eke red m 2 1 170 Pao 700p SO sas ERO 75 6 38 5 397 z LS S3N t 05 40178 ares gg MM21128 t 350 28920 20 pin soiter tan tn 21 26 200 mension 2 035 060 060 PA 150p 500 a 4
93. 50 100 tor 13 00 GREEN 10 for 2 00 100 for 17 00 YELLOW 10ftor 2 00 100 for 17 00 FLASHER LED 5 volt operation red jumbo T 13 size 1 00 each BI POLAR jumbo T 134 size 2 for 1 70 LED HOLDERS Two piece nolder e amp for jumbo LED 10 tor 65 New stereo cassette mechanism Includes record piayback and erase heads 2 12VDC motors drive beits pulleys 3 12VDC Solenoids pinch wheels and other mechanical parts These parts used on other current mode decks would cost several times Our seil ng pr ce i purchased separately 534 X 3 2 X3 a 750EACH 2FOR 12 50 MINI PUSH BUTTON S PS T momentary normaily open bushing Red button 35 each 10 tor 3 00 TOLL FREE ORDERS 4 Siicue onsen rio 1 800 826 5432 ww ide IM CA 1 800 258 8668 TORUGA ORDERS RPO 213 360 8000 iret LAE SE Pe aT TWH 5101010163 ALL ELECTRONIC a cour nes ancats CIRCLE 709 ON FREE INFORMATION CARD 100 tor 5 00 NUTEMTLELLII Bi coo Multi Circuit Board Projects By R A Penfold The Multi Circuit Board Project book contains information that allows the reader to build 21 fairly simple electronic projects all of which may be constructed on the same specially designed printed circuit board In addition wherever possible the same components are used in each design so that with a relatively smal number of CIRCLE 739 ON FREE INFORMATION CARD components it is possible to make any of the project
94. 520 amp N R520 18 NO 8520 JGN SQCRET 8334 END R335 6 NO A236 8 NO AJ3 8 ND A338 6 ND R339 6 ND A340 6 NO R341 ND PCE R423 6 ND 28 R425 6 ND 387 5475 8 ND 58 8428 6 ND 565 R42 6 D 666 5815 4278 amp NO 63 6780 gi 6 2507 43H EAD CARD 177 1326 0 EET 1326 0 3 585 0C B an 705 oc Ba 3H 87901 3H 107650 17230 1 38 C 1214 Of 1430 0t 1755 0i 206 0t 2353 QC Red Grean Amber and Orange Colors Orrect Drive Part No Comm Comm Anode Cath Socket Connector c IStyle SI Digit Color In Red Green Amber Orange Asd Green Amher Orange Rad Green Amber Orange Ret Green Ambar Red Green Amlwi nd reen 50 Wire Wrap to 50 Sokdor Tail micro mchas gold inlay ove a mekel diHtusion barrier Copper nickel tin CA 725 alloy Biturcated contact ports Pralueded cantilever spring design Contacts are use ramovabis H4 SERIES 100 x 200 EDGEBOARD CONNECTORS Pan Mo Bother Tmt C5 10 c5 15 C517 C5 1B c5 20 C4522 C525 C5 2B C5 30 C531 C5 35 C5 36 C5 40 C5 43 C5 39 C5 50 P323 POWERACE 101 Wah pius S to plus 1 VOC Cot No 923101 POWERACE 103 Tp output power suppiy ifto and quiim rt fou numus to Ineiion avadabls Cat No 823103 POWERACE 102 A chgital lab inrlud ng a loge prope aat tock Cat No 821102 ad power supply 1 96 96 PCB Connector e tStyla P1 50 1H N Rheuma omn tet Othe aea CctcoOoUOIUoudocgcouunodcct
95. 614 432 508i 155 560i 1433 13 Big 160 38 Bis 20793 186 a 24 7 158 98 B 76 R104 36 ND R106 6 ND 8106 12 ND 4106 18 ND R106 74 NO R106 36 ND R108 6 ND R108 12 ND A108 18 ND R108 74 ND R108 36 ND R110 6 ND R110 12 NO A110 ta ND A110 2a ND R 10 36 ND R112 5 ND A112 12 NO R112 18 ND 16 68 R112 24 ND 851 A11 36 ND 22 R114 6 ND 13 05 Atia 12 NF 14 87 Aris 418 ME 16 69 R114 24 ND 18 5 R114 36 ND 2215 RTS o ND 24 2 R116 12 NO 26 03 R 16 18 iD 2 89 R116 24 ND 29 73 R116 36 NO 33 38 R118 6 ND 24 27 R118 12 ND 26 09 R118 amp ND 2791 R118 24 ND 29 73 R118 36 Wh 33 38 amp 120 6 ND A120 12 NB R120 1B ND 8120 24 ND R120 36 ND A12 6 ND R122 12 ND 8122 18 ND R122 24 ND R122 36 ND R124 6 ND RI24 17 ND 8124 18 ND R124 24 ND 8124 38 ND R126 G ND H126 12 ND R126 F ND R126 24 ND R126 36 MD R128 6 ND Rt28 12 ND R128 IB D R128 24 ND R128 36 ND R130 6 ND R 30 12 ND A130 18 amp D R130 24 40 R130 36 ND R132 6 ND AIR 12 ND R132 1B ND A132 24 ND Rt32 36 ND A134 6 NO R134 1 I R134 IB NE R134 24 ND R134 36 ND R136 6 N Rt36 12 ND R136 16 ND R136 24 ND R136 36 ND R138 6 NO R138 1 ND R138 8 ND R139 24 ND A138 36 ND R40 6 NO RAO 12 NE R140 18 ND R140 24 ND Hid an wn Rim 50 ND A765 ND R756 10 ND A756 75 ND Am6 50 ND R amp 0 5 ND Rei 10 ND REO 25 ND R amp O 50 ND AMOS ND AFG t0 ND n7 0 25 ND R2 0 50 ND AGI gt A ND Rm t0 ND 1998 60 17
96. 7 58 ass BE2S5 N NN Sing Positron Plog Assembly R8 po 708 7 Dual Pasir Plug Assembly i d UP un un oom YfrrT5588 1404 38 DOWNIN a 37 37 Single Postint Device Mount TO 18 656 26 e160rnnmoudanurnmaoensonv0nnnuto 23b5 fiu 2786 00 3150 Gu 3375 GO 3880 00 3790 00 4210 00 3180 00 Male Fumaia Maie Female Male Ferma Male Femate Single Postin Dave MaunciTO 92 od YYX fa de de 556 6 SZak VSR E nyie Position Bulknead An egtar he 761 X ao NEN AI Dual Position Bulkhead Rei eptacie 263 171 41 O71 76 Port No 41750 ND 411 40 Part No A185 ND 64 90 Pari NE 31760 ND 194 26 13 95 7 50 2 mo bb wia N we 5 dal a8 R QRSEEPIEBENS SESRHESS REET Maie Femate Male Famate Male Femate Male Faemaio tm tp O cb C Ch oh c o o i 3 N i Fiber Opty ible cmi Part N 41700 Desgaers Guide to hur Optics Par No A1798 S866 SESEE BEE oR R E RBSLOENS a ie dA de de do Qv Ua b UL G3 OW i UG G4 BRSSESERELRLBBE Tha D Key volume dacount and service charges axe simple to apply Most dents soid by Digi Key may De combined tor volume discount Items that are not discountabie are identified by the suffix NO foficwsng the pat number After writing yout order ton all of the dicountable nems and apply the appropnate discount To ths subtotal add the non discountable items Then add the senace harge We pay aff shipping and ins
97. 8 241 LCN 06 00 522 amp 47 16 BO 4 L Hie iusso 2 MCN Lm ames 178 PLM3909N 1 38 D COBDRL CN Bo 6324 amp bw 5300 49500 213 TFWM aso suwI wu 6 58 i2 sy 2 9 ER a eee SE DM EM UM 74261N i25 steN 239 oancnN asof 0 fad bree ONDE TET 7B 73 8390 5750 1721 ZWIT 55405120 2200 16 82 785 5539 B 746 219 E2569 250 066 2 1 0533 ae 74365N 3 745197N 2 7AHC390N 75 FA4ACN 75 3 49 DACOR32 UNA 06 B 637 97 50 RO 115 00 Wattage Anang Twan Tin 3300 16 116 9 91 B262 3777 OO 88348 E26R3 250 068 22 185 1543 13883 d 745240N 288 5 393 1758 6ro241N A waiN 3 sap OACTOROLCN 10 50 woes b a eou 59000 Max Working Volvane 4 1700 16 152 1340 11188 157 343 11187 J E2823 2560 0g 22 1 35431 REG 74357N a faszan zeai ancen 18 M96 4 12 LMQUIGN 3af DACio2zi cn 00 MJES B05 6900 5323 ee EY EY 6800 6 39 7700 1M E2104 250 10 23 194 18 3 14513 TAJN bg 745242N 3 TMCSSON 380 MIELNA 245 LM4250CN 2 48 MJE 7B 3 63 00 en Rated 4mbiini Temp 70 C 7PC 2 25 lH 154 1283 2124 250 t 25 212 10756 315869 8093N 78 743243N 3spl ancoxN 360 X7 N 69 f A 7805 90 MJE 12 72 735 6300 Operating Temp Range 55 C to 200 C H 3 18 18 1728 13 178 8934 E2154 z0 05 27 2 895 7055 amp 3 745244N 325 74MC56AN 393 M307N 77 N7806 sof interfece vor 86 806 6900 Dwvension L 130 76 g A 53x u m ia lis 39 ELA p Z X im 25 xe pa 72529 N 1 63i aucevan agi MNN 75 N780 ROT Par Price MsE83 47 830 7800 2 pig itm i ws
98. 80 razor sharp characters per line Even if the computer cannot produce more than 40 characters per line the monochrome characters will still be sharper than those displayed on a TV set In fact the monitor s display is so superior to that of a TV set that most home and family computers provide a com posite video output for conventional color and monochrome monitors in addition to the RF TV set output And when a composite output is not provided aftermarket dealers sell composite video adapters for those computers that are not normally provided with a video output One of the hottest selling retrofit devices is a video output adapter for Radio ON OFF SWITCH POWER SUPPLY HORIZONTAL DEFLECTION YOKE CAP CONTROL PANEL Unlike many other monitors the Heathkit HVM 112A has all the frequently used operating adjustments including a vertical and a horizontal sweep control on the front panel normally concealed behind a small door that swings down Shack s Color Computer which doesn t have an inherent video output A Look At The Monitor Because there is no standard for how many characters and lines are actually transmitted by a home and family comput er Heath s HVM 122A monochrome video monitor has user adjustments that can be used to compensate the size of the screen display for the particular computer with which it is used Firstly there is a 40 80 character switch located on the rear which ins
99. 9 2 3 259 2205 9375 186375 23155N 73 4S51N JAMCIBON 183 1700 Mian 213 NSBTSAN 17 50 5 s E voy uu IU 00 Dimension 06 47 63 21 Y 23 Gps 3 35 43 3690 X750 2 8 34196 aa 74564N MHCI NN 1 69 158 i INS8255N 333 917 23 pin wire wrap goirt 129 1289 12 00 dE 2 4 18 14 116 359 f rza 1 35 1064 9120 76 2767 50 74157N 75 74S65N Jantie LSPA npe ag EN ton wre wap yos 139 1380 13700 Y Metal Tim Veluss n Ohms 100 to 1 00M i5 A DGIEQME JP DO CUP M x E US UE uM 74V80N 951 1S AN PARC AEN i a 3 66 us d d Mba 14 32h C928 Wohin wir wrap gokt 169 1880 no spei Order Take any standard resistor value ice 330 63 2 i n a Z a2 P2088 018 50 E 270 D E 02 75161N ag 74586N JAMCIGAN 558 e an UA aeran OI S one ap pola 229 95 22700 M part Ki ant ado En MIO e auto SM qAS 3 78 25 A iWon s m 3 270 2250 20280 rd mS MM Ho 1 708 M16710 5 59 M5BT4AN3 75 Pricing 5 0 Ec 35 00 3 300 2562 P2021 6 t E P A 3 E 254 E JAY63N 9a 451128 TAN as S 7oliwiezs sso MSMse2 933 Silicon Transistors id amp w we ix 53 8 519 27 S 3 5 35 R02 ne 6 a Ja N 5o 28450 7418AN ga 451 14N J RCATEN 128 75 UMgq298 2 na NSCBOON 2125 d t4 Want coxa xe EP BILIM Nue DSBE M P2034 10 0 i5 35 XQ 2m00 74185N 103 mn 74HC193N 03 1 JOR MISEN 413 NscROD 9 12 a8 Lbs For large quantities and pices low as 68 15 M call BBD 63 12 t e KH yi 795 66 20 P2074 5 0 67 576 4800 13200 74166N 113 s JAHCISAN 10 225i 2o Necnon sog y T 100 1 000 D
100. A OS bela DAN Meis 23 770 890 1 War wm 50925 33 5 iB le 29 rms RO 22 l BaS 7368 930 741 S04N 45 denda 263 rancan i ione 12 m LM7BUSCT 95 75493 Bo osos zi We s 2 Want 18 85 1050 05099 D 7 3 3 09 u8 Hos 33 ASSONTMENT ae 241 SO6N 48 TASI AN 7 SOf Jani asaan 5 33 M32IMP 1528 HM SET ay 5494 42 y beta 21 393 5 siye yuanirtes and prices ae how sa 47 75 M cul Der d 3 n I7 H9 14 js Bf orirorutam CAT NO 95 74L SOBN JSAJAAN goa raHLabasn aof mazomp 22 1 79 m 23 35 a7 1 Watt Resistor Assortments 33 M Me ee M 1 NIE VALUES E KIT SIS TON e samaN a mE w ni s RSY 5 each of valuas 0 479 10 560 2 35 EES 35 3i 278 2315 29 90 0577 4S 11N 74S570N 4 4116 200 nsec 16 nie X FH 255 talal pcs 100 36 43 365 3040 24 206 1710 p z i 45 Signerics SAX an 0925 PU 226 Ui a MU s 1o 04 IC V SERIES 74LS12N as 4551 N 4880pas Price Pree Por Pah Oi Ie 945 Mud BS201 Seach of values 62 10 7 SKR eens 30 35 5 a85 4030 5A 145 3708 Std Mertaliuzen Free Cone sams CEN eo 42N TM o 20 Part NO s m 0 s Uh BD BLK SEE tM pes Ue i ju ne 5 532 451 Operateg Temperature Range 40 s 13 7 P P f e i PESIN m 3 Amenia 16 88 CN 1 T Enero Mass 9590 3400 po x RS3 5 gach ot vaes 8 2KQ to 2 OME sx x 6i 4 2 OE OW EC 2 Capacity Ranga HoFi OuF aii z jACOBCN 236 nin 4 Sik sa P135 t 55 B4 00 770 0 255 total pcs Jw 35 95 74 520N ab 250 ACI40B ON 148 e d 029C 78 fo 1700 14183 Temperature Coefficient
101. AC lines the transmitter connected to one of those lines may not be able to communicate reliably to all remote control modules connected to the other line Intermittent operation may be noticed Any 220 volt AC appliance such as an electric clothes dryer in operation may serve as a temporary path between the two lines However a permanent solution is to connect a l wF 600 WV DC capacitor across the two lines Some experimentation on the remote control module place ment should also help Connecting the Unit The Telephone Remote Control System is equipped with two modular phone plugs labelled Input and Output Those plugs are designed to be plugged into a modular jack See Fig 9 If your home or phone does not have a modular phone jack you may install one yourself or have the phone company install one Ma Bell will charge for that service If your home is equipped with an older style four pin jack you can convert it to a modular phone jack with an adapter Adapters may be purchased at your local phone company or electronics parts store Single Telephone Installation Here s the step by step procedure for connecting the the Telephone Remote Control System to the telephone line for a single telephone system l Disconnect existing telephone modular phone plug from wall phone plate Refer to Fig 9 2 Insert Control System modular phone plug la belled input into modular phone jack in wall phone plate 3 Insert Control Sys
102. AP Products dealer today or send for a list of dealers in your area A N CIRCLE 706 ON FREE INFORMATION CARD Sf ag SE M Oe e SOUS QR a 4 NOME MINER HENCE M LEE UE dnd do even more with our 40 breadboard A P PRODUCTS INCORPORATED 9325 Progress Parkway P O Box 540 Mentor Ohio 44060 800 321 9668 Ohio 216 354 2101 F S g c e HANDS ON ELECTRONICS A Vintage Radio Kit Help Is there someone or some com pany that sells a kit of parts for the Vintage Radio published in your Fall 1984 2 issue of Hands on Elec tronics repeat Heeelp M B Richboro PA Yes First many readers write to us for plans on the 1920 Style Wireless He ceiver we called it the Unidyne that were published in the above issue The issue is Still available although the sup ply is limited You can obtain your back issue by writing to our New York office Be sure to include 4 00 for the issue and 1 00 for postage and handling A kit of parts is available from Tech nicraft Electronics by writing to them at 338 Katoomba Street Katoomba N S W 2780 Australia Send two Inter national Reply Coupons for a response on their latest prices and information on other vintage radio kits The above information holds true for DICK SMITH S FUN WAY INTO ELECTRONICS Join the thousands of people youn and old who have discovered Dic Smith s Fun Way into Electron
103. BCD to 7 segment decoder driver integrated circuit U2 U8 CD4518 dual up counter integrated circuit U4 CD4013 dual D type flip flop integrated circuit US CD4081 quad two input nano gate integrated cir cuit U6 CD4084 hex Schmitt trigger integrated circuit RESISTORS All resistors are 1 4 watt 5 units RH1 100 000 ohm H2 R4 R6 2200 ohm R3 220 000 ohm R7 R36 100 ohm CAPACITORS Ci 0 02 uF 25 WVDC electrolytic C2 C3 0 05 uF 25 WVDC electrolytic C4 100 uF 16 WVDC electrolytic ADDITIONAL PARTS AND MATERIALS S1 S3 Normally open pushbutton switch NOTE Two of each semiconducting resistive and ca pacitive components listed above except C4 only one required are needed to assemble the project Printed circuit material 4 C or D cell batteries and hold er or 6 volt 200 mA plug in wall power supply en Closure wire solder hardware etc The Digital Cribbage Board s printed circuit board part No CR 7 is available from Electronics Enterprises priced at 14 95 plus 1 50 for postage and handling 3305 Pesanta Way Livermore CA 94550 Please allow 6 to 8 weeks for delivery 9861 g3J NVf h gi HANDS ON ELECTRONICS h2 o Fig 3 The parts layout for the Digital Criboage Board shows that two matching circuit boards make up the entire proj ect Component designa tions are duplicated in each half That means that two U1 s two U2 s and so on are neede
104. D ens URP ene UND UND Re UND Gb UP uum GER GER GR cm m UNES Continued on page 106 e A Digital Fundamentals Continued from page 90 AFTER 4 SHIFT PULSES A vo EEA ORIGINAL STATE AFTER ORIGINAL STATE PRESET SHIFT PULSES s GERI enge dioe Fig Geen er selec for 9 serial to parallel conversion and B parallel to serial conversion BYTE BYTE BYTE BYTE BYTE BYTE 31 30 29 2 1 0 Fig 18 A 256 bit shift register used as a serial memory to store 32 bits of data in Fig 18 The data is entered serially and read out serially Because there are so many flip flops parallel output is not feasible Figure 19 shows a complete circuit for using the 256 bit shift register as a memory The gates at the input of the shift register are used for entering serial data when it 1s desired to store a byte and for data recirculation When clock pulses are applied to a shift register data that is shifted out is generally lost However it doesn t have to be By taking the serial output of the shift register and feeding it back into the shift register input as the serial word is read out it is restored at the input That is accomplished with gates A and C at the input to the shift register The CONTROL line is used to select whether new serial data is to be stored or whether recirculation is to be accomplished When the CONTROL input is high the shift register will recirculate Serial data output is fed to gate a w
105. ER amp NUMERICAL DIS PLAY PROJECTS 4 50 Numerical indica tor devices make it easy to count divide and dis play ELECTRONIC TECHNOLOGY TODAY INC P O Box 240 Massapequa Park NY 11762 0240 Battleships Calendar the sun and more 247 pages 7 10 n shows equivs and pin connections for popular user oriented ICS NOLOGY EXPLAINED sees 5 00 Explanations for computer terms often encountered A dictionary for Computer lingo CHINE CODE 5 75 Speed up your programs They may be harder to write but its worth learn ing how Some demo programs are included ECTS 5 00 Practical radio antenna designs that deliver good performance and are rei atively simple and inexpensive to build Kiectronice How 1o Denign ow to het Your lectronic amp impfified Ei ce lectronic x eid Project Saien Crystal Set Guide Projects Projects Construction HANDBOOK OF IC EQUIVALENTS AND SUBSTITUTES 5 00 Includes digilai and linear ICs made in US Great Britain Japan etc DESIGN amp MAKE YOUR OWN PC BOARDS 5 75 Ev erything you need to Know before you make printed circuit boards for your projects HOW TO GET YOUR ELECTRONIC PROJ ECTS WORKING 5 00 How to find tne faults in your projects re pair them and get them working ELECTRONIC TIMER PROJECTS 5 00 Timing circuits to fil just about every application Required for every ex perimenter
106. ES OFF 9 DOOR 2 INTERIOR ON 12 VOLT CAR LIGHT Nu I INDIVIDUAL BATTERY 7 DOOR ER SWITCHES KEY SWITCH t I 1 l E nu REVISED POSITION 2 X 22uF TANTALUM Fig 6 The schematic diagram for the Auto Alarm circuit differs from the circuit in Fig 1 in that it only has One sensor input and no socket is provided for an alternate power source Fig 5 Wiring scheme for installing the Alarm in an auto The dotted line represents the wire that connects the sensors to the Alarm circuit at the open end of R2 and the pushbutton switches represent the sensors located at various openings simplifies things since no mounting hardware is required A four way block at one end connects to the sensing loops represented by the switches in Fig 5 while a six way at the other end connects to the battery key switch and signaling device A separate 3 5 mm socket is fitted to the case to ac commodate the plug of an external power supply We have shown the Alarm system powered by a plug in power supply and backed up by a battery in case of a power failure The battery can be an external type such as a large 12 volt unit to give lIMAGINE BEING ABLE TO TUNE IN ON the world with your own shortwave re ceiver Well you can with this project ts simple to build and uses a CMOS integrated circuit to provide enough am plification to drive a loudspeaker With it you can tune in shortwave
107. Make sure that all components are dressed neatly positioned before soldering them in place Mount the LED the anode positive lead is the longer of the two and goes towards the outer edge of the PC board The LED can be soldered in place as shown or tacked to the opposite side see photo Which ever side iS PARTS LIST FOR THE MULTI PURPOSE LED FLASHER LEDi Jumbo red light emitting diode TRI TR2 D5548 ECG123A 2N2222 2N2222A or similar NPN transistor H1 330 ohm walt 5 fixed resistor R2 H3 47 000 ohm Va watt 5 fixed resistor H4 550 ohm Va watt 5 fixed resistor C1 2 2 uF 16 WVDC tantalum capacitor C2 10 uF 16 WVDC tantalum capacitor ADDITIONAL PARTS AND MATERIALS Battery snap solder hookup wire 9 volt battery or other 9 volt DC source optional LED identical to LED1 suitable mounting board or printed circuit board of correct design The Dick Smith K 2621 Flasher Kit contains the printed circuit Order the Flasher Kit of parts K 2621 for 2 95 from Dick Smith Electronics Telephone 1 800 332 5373 and tell them you saw it in Hands on Electronics chosen a link jumper wire must be sol dered in the opposite position labeled LINK Position and solder TR and TR2 If you are unsure about your soldering abil ity use a heatsink on the transistor leads to prevent overheating Solder in the battery wires again taking care with polarity There s not much good getting everything els
108. NDUC M Factory Firsts SC CHEMICALS A LE uw INTEGRATED CIRCUITS i Ti iC SOCKETS T TANTALUM CAPACITORS JALS157N 88 74C373N 313 MEN TA 35 313 2 APLM7BLOSACZ 55 ia 110 88 ssa iwzscizacz si SOLDER TAIL f 110 aa E IM78 5AC2 558 DIP SOCKETS a No Cep Voit 100 100 1 000 nic KEY cy e on on ES 130 BE LMJ 1 i P4000 J a 110 queen si Singe beam 10 pt 500 75 548 ag 7 7000 33 31 ki 2 2250 20200 Ps 105 12 06 nisser ide t tow profile a MOI P NE 3e ogre Seas d ie ak SEX Nan S 4X3 igp 500 5 49 48 7 3
109. ORMATION CARD iai CIRCLE 711 ON FREE INFORMATION CARD LISCANNER FOLKS KEEP MAKING THE headlines although all of the news isn t that good One of the more interesting items to recently show up tells of Junior Bel lomy of Muncie IN This guy s an enthu siastic scanner user and keeps his scanner tuned in on the pulse of his community While monitoring his local police fre quency he overheard a national police bulletin issued by the police in Madeira Beach FL They were looking for an auto theft suspect who was also wanted for questioning in a murder Bellomy thought the suspect s name had a familiar ring it was a name that was identical to that of his 20 year old nephew who was visiting Muncie trom Florida Bellomy drove over to the Muncie PD station house and asked the Captain if it was his nephew that they were seeking After hearing Bellomy s description the police agreed that it was indeed just the man they wanted What could be easier Bellomy told the Captain that the suspect was out in the car The police promptly arrested the young man who was being sought by the Florida agency On the darker side of the headlines a VHF enthusiast with a powerful transmit ter tuned it to a frequency where it didn t belong a few months ago Police in Portland Oregon reported that they were looking for the wiseguy who spent about an hour deliberately jam ming the communications of that city s Bureau
110. OTE CONTROLLER 2995 18 00 ea ZENITH SSAVI CABLE READY DEALER PRICE BASED ON 5 UNITS 225 00 185 00 ea SPECIFY CHA NNEL 2 or 3 OUTPUT Other products available Please Call Output Quantity Item Channel California Penal Code 593 D forbids us SUBTOTAL from shipping any cable descrambling unit Shipping Add to anyone residing in the state of California 3 00 per unit Prices subject to change without notice onan 3 rea PLEASE PRINT TOTAL Name Address City State Zip Phone Number Cashier s Check Money Order COD Mastercard Acct Exp Date Signature FOR OUR RECORDS DECLARATION OF AUTHORIZED USE the undersigned do hereby deciare under penalty of perjury thatall products purchased now and in the future will only be used on cable TV systems with proper authorization from iocal officiais or cable company officials in accordance with all applicable federal and state taws Dated Signed Pacific Cable Company Inc 7325 RESEDA BLVD DEPT t RESEDA CA 91335 818 716 5914 No Collect Calls 818 716 5140 IMPORTANT WHEN CALLING FOR INFORMATION Please have the make and model of the equipment used in your area Thank You 986 H34 NVf ET m HANDS ON ELECTRONICS e New Products Showcase Continued from page 8 they developed a technique that produces oversize Copper crystals called logically enough giant crystals Then they de vised a copper extrusion process that stretche
111. P Co C2 HANDS ON ELECTRONICS o A This is what the kit looks like with the circuits in place ready for the rear cover It might appear to be messy because of the connecting wires between the assemblies but everything is rigidly mounted and secure when the cover is installed simply adjust the vERTICAL SIZE control until the display regardless what it is fills most or all of the screen Other HVM 122A features in VIDEO BOARD clude a 15 MHz bandwidth a 12 30 ANGLE inch diagonal screen and an RCA type phono jack that accepts an NTSC volt peak to peak input signal It takes about two evenings to build the kit As is typical of most Heathkits there is little factory assembly of anything even the tweaking adjustment for the hori zontal coil must be user assembled In fact the only item that s factory installed is the CRT which comes firmly clamped inside the monitor cabinet see photos Lots of Diagrams Although most of the monitor is assembled on a large printed circuit board that simply slides into the base of the cabinet there are six small subassemblies that are connected to it To simplify the assembly and interconnection of the various boards and parts a sepa rate illustration booklet is provided along with the usual step by step assembly manual The booklet treats each individual assembly as a separate project and provides pictorials of only the parts used by that assembly A separate pictor
112. PLEASE INDICATE in which category of classified advertising you wish your ad to appear For special headings there is a surcharge of 10 00 Plans Kits Business Opportunities For Sale Education Instruction Wanted Satellite Television Special Category 10 00 PLEASE PRINT EACH WORD SEPARATELY IN BLOCK LETTERS No refunds or credits for typesetting errors can be made unless you clearly print or type your copy Rates indicated are for standard style classified ads only See below for additional charges for special ads Minimum 15 words M M OR I MM 2 3 4 5 BO TEES 8 9 10 TEE IE MEME IEEE IEEE T ILLUM 16 20 00 17 21 25 18 22 50 19 82375 20 2500 21 26 25 22 627 50 23 28 75 24 3000 25 3125 26 32 50 27 33 75 28 35 00 29 3625 30 3750 31 38 75 32 44 00 33 4125 34 842 50 35 43 75 We accept MasterCard and Visa for payment of orders If you wish to use your credit card to pay for your ad fill in the following additional information Sorry no telephone orders can be accepted Card Number Expiration Date PRINT NAME SIGNATURE IF YOU USE A BOX NUMBER YOU MUST INCLUDE YOUR PERMANENT ADDRESS AND PHONE NUMBER FOR OUR FILES ADS SUBMITTED WITHOUT THIS INFORMATION WILL NOT BE ACCEPTED CLASSIFIED COMMERCIAL RATE for firms or individuals offering commercial products or services 1 25 per word prepaid no charge for ZIP code MINIMUM 15 WORDS 10
113. T LEAST 1 1 SIGNIFICANT A g Q rc DIGIT DIGIT LSD MSD c gt COUNT INPUT m OD Fig 11 Schematic diagram for a BCD counter All uncon Hes HUNDREDS nected J and K inputs are connected to a binary high 1 Fig 13 Cascaded BCD counters e eo 12 3 a S 8 7 8 589 10 11 432 13 14 15 16 serial pulse train that occurs in synchronism with the shift INPUT JUUUUUU ULL fk clock pulses applied to the input will be entered into the shift HANDS ON ELECTRONICS e Fig 14 Logic diagram for a 4 bit shift register shown in Fig 13 will produce frequency division by some multiple of 10 The first BCD counter will divide the input frequency by 10 The D output will be one tenth the frequen cy of the input The second counter will produce division by 100 while the third will produce division by 1000 Both binary and BCD counters can be used in counting and frequency dividing applications at very high frequencies Standard TTL MSI counters can achieve speeds upward of 50 MHz Schottky TTL counters can achieve speeds up to 125 MHz CMOS counters have a much lower limit of approx imately 25 MHz but progress is being made in extending that frequency capability ECL counters are available for frequen cies up to 2 GHz Shift Registers Another sequential circuit made up of flip flops is the shift register Like a counter multiple flip flops are used to store a binary word However the flip flops a
114. TODAY S BEST SURPLUS BUYS IS THE LOADED printed circuit board The experimenter can buy a board containing a dozen or more digital IC s and other useful parts for less than a dollar Usually the IC s alone are worth several times the price of the board Unfortunately many of the best boards are passed up by the hobbyist because the IC s are not marked with recognizable industry standard numbers There is a solution to the problem of unmarked IC s This article describes a way to make TTL DTL and even RTL IC chips sign in once they are removed from the board The IC signature shows you which pin is V and which is ground The IC signature tells you which pins are probably output terminals And it requires nothing more than a piece of paper and an ohmmeter After that a few voltage and current measurements and you should know what kind of IC you ve got Here s how it works An IC signature is an array of resistance readings derived from the IC and displayed in an organized way The Xx 100 range of an ohmmeter is used Be sure that you know which ohmmeter lead is positive some ohmmeters change polarity when switching from volts to ohms especially in the low ohm ranges The signature is obtained by recording the resistances between all terminal pairs of the IC Use the signature chart shown in Fig 1 Connect the chmmeter s positive lead to pin 1 and move the negative lead sequentially through the re maining pins 3 4 5 etc Record t
115. Tezulutaln 4 835 kHz can be heard with lovely marimba music during the early evenings Ecuador Emisora Gran Colombia in the capital Quito has been putting de cent signals into North America recently French Guiana Cayenne s shortwave station in French can be found operating On 5 055 KHz Guyana This small country on the shoulder of South America used to be called British Guiana before indepen dence The Guyana Broadcasting Service station at Georgetown broadcasts or 5 950 kHz It is best heard early in the morning about 0930 UTC GMT Nicaragua Sometimes interesting les tening from this controversial Central American nation La Voz de Nicaraguc has English programing about 0130 GMT UTC on 6 015 kHz This 5 inch full color decal was sent to listeners by stations belonging to the Caracol Broadcasting Network in Columbia Costa Rica Another Spanish language station is Radio Impacto a commercia operation in San Jose It broadcasts on 6 150 kHz Listen around 1100 or 0200 GMT UTC There are literally hundreds more to hear from Latin America There s no way I can list even a small proportion of those stations Inside the Oscilloscope Continued from page 93 stance failing to be sure that the vER TICAL attenuator and the time base are in their calibrated positions Other similar errors include the failure to compensate the probes see Selecting the Best Voltage Probe page 28 Nov Dec 1985 im
116. USES e JACKS amp PLUGS e KNOBS e LAMPS e POTENTIOMETERS a RF COILS e RELAYS e RESISTORS e SWITCHES e SEMICONDUCTORS e SPEAKERS e TEST EQUIPMENT e TRANSFORMERS e TOOLS e WIRE amp CABLE OVER 15 000 OIFFERENT ITEMS IN STOCK Phone ond Mail Orders Welcome Catalogs Mailed Outside USA Send 2 00 Soles ond Order Desk Open trom 6 000 m IPSTI e TERMS COO Vna MasterCharge Open Accounts Availahle MOUSER ELECTRONICS i432 WOORSIDE AVE SANTEE Ca S2071 PHONE 619 449 2222 TWX 910 331 1175 CIRCLE 714 ON FREE INFORMATION CARD Get professional quality at home KeproClad is the quick easy and inexpen sive approach to home production of quality printed circuit boards Minimum investment required IRL i Complete package eem packaged pre sensi tized negative acting kepro Extremely rugged yet holds fine lines sided copper foil Developer included For your local distributor write or call KeproClad comes 4 dry film photoresist Available in two sizes with one or two 1 800 325 3878 1 314 343 1630 in Missouri m Kepro Circuit Systems In 630 Axminister Drive Fenton MO 63026 2992 CIRCLE 713 ON FREE INFORMATION CARD CADEA ON DX IN By Don Jensen Listen to the lands of the tango cumbia mariachi and huayno IN THE PAST FEW COLUMNS WE VE taken an overview of the world continent by continent looking at the different countries and their shortwave stations This time
117. WRAP 11 13 16 26 24 atc through 910k a te x 58 3 B3 3673 P2084 720 70 BT a960 41860 373500 T 74H COON on f 458 125 1 38 sasa7gan B25 1360 total pcs PAXA Om a 9 24 32 Pd 23 16 3 270 2250 20250 T n 2m 2 2 MHCOON o8 vid 2 745570 AC DIP SOCKETS cect 1 4 Wen Carbon Film Assortments P4307 a7 s 25 E a p E rm 1 18 3 2 En 2 ES 220 E 74 S Em re e 2036 35 ipie E 2 03 ILMIN 234 pci 3 bed Standard profils 1 RS125 5 each of the 73 standard values in sanas 69 90 pe 25 tw 15 37 11531 E P2037 3 15 a 325 E E E go 60 MRCION a8 BIILV3838T 3713 288 Universal mounting end 10 12 1 1 8 22 wc through OM NPO NPO NPO NPO NFO NPO APO NPO P2038 10 16 81 513 325 39825 En 7aNClIN 6 5 ED NR Pu Prset c lapis uu dudas PAAQ Cp OT 28 I um X meum mr d MHCISN 123 abveemw 206 maaien is 296 Sanjata acotmmodat ASZ each of the 72 standard values in senes 8 39 9 P4a02 15 pf co m E ei 2 E DE 5 a ub JEN 5E rec n y i 74 AEN 130 rM388N 3 2 154 9290 ND 1 or round doai In ine leads DEUS din EDEN te arenas MOS Eas ent 500 8 97 52 31 poe i l4 227 1950 16250 146250 HL iieri e i gajim 184 a Wire wrep poste heid to true position of 015 pro 1360 total pes Paa 22o 40 g 697 jp Eie z 18 275 2370 19750 177750 a Q 3 phaea 7aHC32N 52 75 Hed i Micro viding true position of 020 on boards fo effi 1 2 Went Carbon Film Assortments enel X e es A B9 86 r208 150 i8 is E n E tp Sg D
118. When New Liquidation Price Now Only item H 796 63831 00 Ship handling 7 00 Price subject to change after 60 days Sales outside continental U S are subjectto special conditions Please call or write to inquire Credit card customers can BEEN order by phone 24 hours VISA omercano a day 7 days a week 7 90 Toll Free 1 800 328 0609 day Fai Your check is welcome 64 K 1 Limited No delays in orders paid by check M Factory TeleCheck MODEM ara Se Muir eae ps at C O M B Direct Marketing Corp Item H 796 Liquidation due to manufacturer s overproduction The l 14605 28th Ave N Minneapolis MN 55441 3397 modem plugs into Commodore 64K or SX64 so you can access new worlds of information on a subscription 2 basis Has modular jacks for quick hookup to phone Works on TouchTone and Rotary Pulse systems not PBX Super intelligent software completely menu driven 30K software buffer Auto dial auto answer Price includes FREE triai subscription to over 52 database services Mfr List 124 95 Liquidation Price 1 Q l Item H 796 63646 00 Ship handling 4 00 C O M B Oirect Marketing Corp Authorized Liquidator 14605 28th AVENUE NORTH MINNEAPOLIS MINNESOTA 55441 3397 nd the following items Minnesota residents add 6 sales tax ow 3 4 weeks for delivery Sorry no C O D __ Dot Matrix Printer s Item H 796 63831 00 at 119 each plus 7 each for shipping and
119. a Violet pum ins Uitte DO 41 1 E 1200 100 00 71 006 stow To Order Take any aa e Kos n amp J s Sts Ja eel 5602 ras oon 12 112 98 72 s F 3 4 r y 4 0 J9 511 r anrai alue lt E a ESSON ls N 591N 28 5 296 25 IARE 28 Din 675 Swiching Dice 500 27958 2175 and WS for 5 wan or add AND tor i0 Wan es 370 63 105 B94 1442 39 ra Es Pasig 9 033 13 119 1523 73 40 re t T 2 3 Rus E een Z6 ps 3 AMP SILICON RECTIFIERS Pricing 13 6 so o0 727 WO 5 ih E 3 P P4521 0 047 15 132 1139 8290 Mt M NESEN 058 EE MICCODLOCE Ages RIA jm 000 375 1 000 5 wen 2259 oo mo fi 55 pa x19 Baj ce s sx zo NI FALTIN 22 100 185 4523 a n x ULNZX3 46 DighKey de LH 10 Wan Cae x Nes Xe ALIS GE QR Sd Ban 7 153 0319 3690 MALE be 5 ULN2004 1 469 Pact No Description Each For large quentdwe and poces as hive 3 VI 4 com Dey gt ay a 100 28 2 3 18953 1 gt a 1790 Manus n wz a o1 039 10270 24 8123 TOAZBOA 2 70 D8748HC 8 Bn Microcompure 40D 31575 5 Watt Resistor Assurtments 10 00 3 278 2315 22 183 1518 m 1 taag 105 40 LS123N 13 TOA103 2568 pe p o 1575 22 100 43 365 304p 27 227 mag GPEC 12 20 181 1562 380 741 125N 68 EBEN PM parenn B Bn Mi rocomputer _ Dm 1855 053 j AS105 5 aach of valuns G IOR to 0 910 e795 12 i0 a 3a v0 4 fS i Rea 74151266 6B Tao 3E anMerecompeter s ac 20 peel im me nas oe D 4 2 2 JALSN 108 ioa 3g DENSAC Sege Cho 8 og e PE Op BBS Pan RS206 4 vach of values 1 OR to 9 19 27 96 220 1
120. a matcher with added features This MFJ product is the 949 C Deluxe Versa Tuner It uses a cross needle meter that reads foward power reflected power and SWR simultaneously on either 30 or 300 watt scales with an impedance bridge will testify the real life ground plane using four quarter wave radials is a vastly different device Strangely enough the true situation has been known for many years At least as early as 1962 when it was stated that the radiation resistance of a ground quarter wave antenna is 35 ohms but that of a ground plane is less than 20 ohms More recently other authorities have been emphasizing that same point but unfortunately old ideas die hard and the point needs to be emphasized a good deal more strongly if the error is to be corrected But that is a separate argument The point we set out to make is that apart from those few simple designs it is exceedingly difficult to nominate the feed point impedance of an antenna We do know the general effect of many design factors that for example the addition of director or reflector elements to a dipole will lower the impedance But by how much is another matter So we are faced with the situation that the impedance of all but the simplest antenna systems is largely an unknown quantity With experience we can make a rough estimation that it will be between this and that figure or below some other figure but beyond that we must resort to some form of measuremen
121. a window and reaches in for the goodies While this kit won t prevent the window being broken it will protect your property inside the car Silent ultra sonic rays detect any movement and trigger the EA USE WITH YOUR EXISTING ALARM OR THE DICK SMITH CAR ALARM Cat K 3252 Two Compact Radar Detectors Uniden has added two compact radar detectors to their line The model RD 9 measuring only 4 2 x 2 76 x 0 7l inches may be the smallest self contained radar detector currently on the market It IS very sensitive and features separate X CIRCLE 734 ON FREE INFORMATION CARD and K band LED and audio indicators The RD 9 also teatures Electronic Data Interference Terminator E D I T cir cuitry which assures accurate radar signal detection by helping to eliminate er roneous signal interference Housed in a pocket sized carrying case the dual con version superheterodyne radar detector can be installed in almost any size vehi cle A two position highway city selector switch allows the user to select unfiltered Continued on page 8 The Dick Smith more FEATURES access normally open or normally closed in any mix Inbuilt mains power supply with battery backup also capable of driving telephone diallers strobes etc Inbuilt local test facilities including buzzer Complete kit including case and all electronics Cat K 3424 w amp amp m NLY SIS OQ VCR Theft Alarm That VCR sitting on top of y
122. aborate functions By Warren Baker L WHEN IT COMES TO DESIGNING ANYTHING ELECTRONIC these days you are almost sure to need some form of timing circuit Well for almost any timing function the amazing little NE555 oscillator timer is nearly unmatched in its field One need only consider simplicity of design ease of assem S1 oy RESET e fguT They allow you to stop the timing cycle at any point Once the RESET switch Sl makes contact the timer remains in that state until the sTART Switch 52 is pressed When either switch is activated LED READY and the TIME indicator LED2 keep track of the situation Although not necessary the two light emitting diodes should be of dif ferent colors say red for READY and green for TIME for zn rcm JUST ra START Fig 1 Note the simplicity of the Adjustable Timer A 4 single resistor R1 a 2 5 Megohm potentiometer makes the timing of the circuit continuously adjustable HANDS ON ELECTRONICS go N t 14 1X RICI t TIME f FREQUENCY E tl bly and low cost to see why that unit as a circuit building block is hard to beat The timing circuit described below exemplifies each of the NE555 s capabilities in an easily duplicated circuit that may even serve a useful purpose in your own design projects Simple Timing Circuit A quick glance at the schematic diagram in Fig will reveal the ease with which the unit may be assembled The circuit
123. along with dedicated separate power supply and IDEAS 42 PROJECTS COMPLETE PARTS LISTS ONE EVENING PROJECTS EASY TO BUILD often a fan for cooling While there are variations in the way external hard disk units connect to various computers most retain the same kind of controller board used for internal hard disk The difference between them is that the external drive mechanism connects to the computer through cables that provide for some kind of disconnect of the unit As far as operation of the hard disk drive is concerned there are only two sub stantial differences between the internal and external hard disk The external hard disk does not result in loss of a floppy and it can be independently turned off by sim ply turning off its power The external expansion hard disk up grade is usually possible only for IBM compatible computers which normally have five or less expansion slots One of those slots must be used by the floppy disk controller and another by the monitor adaptor With the hard disk controller three of the five slots are used leaving only two empty slots for additional expan sion which isn t much when you con sider the great variety of accessories available for the IBM PC s One of the most convenient ways to get around the shortage of expansion slots and still use a hard disk is to use an exter nal expansion hard disk upgrade The external expansion type is basically sim ilar to the
124. amber light emitting di ode LED3 Jumbo red light emitting diode Fi A3 z2 7 000 ohm 2 watt resistor see text Fi4 AG H7 R9 100 000 ohms Ve watt 1 resistor see text H5 2200 ehm Ve watt resistor HB8 50 6D0 ohm Ve watt resistor U1 7815T positive 15 volt regulator Radhi Shack 276 1772 U2 7915T negative 15 volt regulator U3 LM339N quad comparator integrated circuit Qe dio Shack 4276 1712 fe N 986 G34 NV HANDS ON ELECTRONICS ie eo By Herb Friedman m DNAN ON COMPUTERS A hard disk system can give your personal computer the power it needs to handle almost any large application program available L WHILE THE DOUBLE SIDED FLOPPY disks that are common to the new genera tion of computers are generally more than adequate for single application programs modern multi function programs are often so large that just the program it self without its data files can easily approach the capacity of the double sided floppy disk And even routine use of such software can require frequent time con suming and annoying disk swaps From word processing to spreadsheets to CAD computer aided design much of the latest software requires on line disk stor age that s substantially greater than that of the conventional double sided floppy disk Although it is possible to attain such storage by using one or more high density floppy disk drives such as the one u
125. and electronic title sets for professional looking control panels WRITE FOR IT NOW The DATAK Corporation 65 71st Street Guttenberg NJ 07093 CIRCLE 710 ON FREE INFORMATION CARD One tree can make 3 000 000 matches One match can burn 3 000 000 trees ms 9861 83Jd NVP uo HANDS ON ELECTRONICS eo PERSONAL DEFENSE AND PROPERTY PROTECTION sa UTILIZE SPACE AGE TECHNOLOGY CAUTION THESE DEVICES CAN BE HAZARDOUS AND MAY SOON BE ILLEGAL A POCKET PAIN FIELD GENERATOR IPG50 S Assembled 64 50 IPG5 Pians 8 00 IPGSK Kit Plans 44 50 g PHASORPAIN FIELD CROWD CONTROLLER PPF10 Assembled 250 00 l PPF1 Plans 1500 PPF1K Ki Plans 175 00 xy BLASTER Provides a plasma discharge capable of puncturing L 3 E A S M Me a can Produces a 100 000 WATT PULSE BLS10 ASSEMBLED BLS1 PLANS 10 00 BLS1K 89 50 KTIPLANS 69 50 PLASMA STUN GUN Very intimidating and affective 5 to 10 feet 100 000 VOLTS ITM10 ITM1 PLANS ASSEMBLED 99 10 00 ITMIK KIT PLANS 69 50 90 RUBY LASER RAY GUN Intense visible red beam burns and welds hardest of metals MAY BE HAZARDOUS RUB3AII Parts Available for Completing Device 15 00 CARBON DIOXIDE BURNING CUTTING LASER Pro duces a continuous beam of highenergy MAY BEHAZARDOUS LCS Al Parts Available tor Completing Device 15 00 VISIBLE LASER LIGHT GUN produces intense red beam for sighting spott
126. aps the easiest way is to connect fine wires and hide the battery in your pocket or behind Fig 4 There is plenty of room inside the smallest Zippy box for the printed circuit A hole is drilled in the front panel for the LED to poke through Fig 5 A same size pattern of the LED flasher board for electronic jewelry Cut the circle shape with a hacksaw and finish off with a file your collar The badge itself can be held on by a tab of double sided adhesive tape available from most stationary and other stores or a normal pin clasp glued to the back of the board Another suggestion is to mount the brooch on a gold chain and use the chain itself to carry power down to the board Obviously the two halves of the chain would have to be insulated from each other Another idea we ve seen is to have the circuit worn behind a jumper or tee shirt with the LED s poked through fine holes between the strands of fabric That idea looks really neat if the jumper or teeshirt has a design or pattern on it that can be worked in with the LED s However the most logical idea as far as convenience goes is to actually mount the batteries on the back of the board itself Use small silver oxide or mercury batteries the type used in watch es The drawing and photos should give you a good idea of how to make up your own brooch or badge Once you ve made up your printed cir cuit board you must decide whether you re going to
127. ard it is necessary that the foil 9 pattern of Fig 6 line up as close as possible with the above when preparing to etch your own board points produces the all lights on condition Usually those points are connected to an existing alarm system s normally open contacts Connections E3 and E4 should be soldered to the red and green wires respectively of the modular phone extension cord That part may be bought at Radio Shack or made up if you purchase the items required separately and have access to a modular crimping tool That line should be tagged Output to distinguish it from the other modular phone extension cord s red and green wires which should be connected to E5 and E6 respectively and tagged nput When the LM341 US is positioned on the printed circuit board the voltage regulator heat sink may protrude slightly outside the printed circuit board area The excess should be trimmed off if you re using the Radio Shack case A good pair of pliers does the job nicely The LM341 should then be soldered to the printed circuit board heat sink or as a mini mum you should apply some silicon between the board and Fig 8 Parts placement for the Control System s printed circuit board Note the orientation of the IC s which have all their notches facing in the same direction That allows you to spot at a glance any misoriented IC the voltage regulator before soldering the three terminals Integrated circuit U4 could be
128. ards together with short lengths about 30 mm or so of hook up wire Those jumpers should go from the component side of the second board to the trace side of the first It is fairly easy to solder to the copper pads just be careful that you don t bridge short two pads together All that remains is to connect the bat tery and push the button Both rows of LED s should come on dimly as above with one LED in each row glowing bright ly when you release the button Both Fig 5 Two Dice PC boards fit easily into the box The addition of the extra board is the only difference between this figure and Fig 3 LED s should then die out at about the same rate If you wish to mount the dual dice in a project box you will have to drill a second row of holes as shown in Fig 5 The second board mounts three slots behind the first to allow the LED s to line up You may need to lay over capacitor C1 to allow for the close spacing That gives plenty of room for the battery to lie in front of board when both boards are in the box E um Jat e lt gt AMPLIFIER This easy to build amplifier circuit has several useful applications ranging from audio amplification to electronic troubleshooting JONE OF THE MOST POPULAR PROJECTS for the electronics hobbyist is the audio amplifier After all an audio amplifier is particularly useful As well as the more obvious uses it can be used to trou bleshoot other proje
129. are cascaded as in a standard 4 bit binary counter with the normal output connected to the clock input of the next flip flop in the chain The last flip flop on the other hand has its clock T input connected to the normal output of the A flip flop Note that the signal controlling the J input on the D flip flop is derived from an AND gate that monitors flip flops B and C Also note that the complement output of the D flip flop is fed back to the J input of the B flip flop The result of all those unusual inter connections is that the counter has only ten states instead of the usual l6 for a 4 bit counter The counter counts in the BCD sequence previously described in Fig 10 The waveforms generated by the BCD counter are shown in Fig 12 The counter counts from 0 0000 to 9 1001 in the normal sequence When the tenth input pulse is received trailing edge the counter recycles to O and the sequence repeats The operation of that counter is generally similar to a 4 bit binary counter That is particularly true of the first eight states from 0000 through 0111 The A B and C flip flops toggle off and on as you learned previously After the 7th input pulse the output states are 0111 The B and C outputs are high thereby enabling the AND gate which applies a binary to the J input of the D flip flop At that point the flip flop is enabled and will toggle when a trailing edge signal appears at the clock input That happens when the eighth
130. are to ensure that Cl C2 C4 and C6 are correctly oriented When mounting the two audio transformers be very careful to ensure that you have the correct one in the correct place and facing in the right direction Note that the coup ling transformer has three wires on each side but that only two are used on the primary side the spare one should be bent upward and out of the way The output transformer has three wires one center tap on the primary side and only two on the secondary or output side Although they look very similar those transformers are definitely not inter changeable Once the transformers are in place solder the diode in again ensuring that it s correctly oriented Carefully place the four transistors so that their leads contact the right pads and solder them in using a heatsink to prevent damage from overheating Next connect and solder the speaker wires to the board and then to the speaker making sure that you do not damage the speaker by overheating Solder the wires from the battery snap to the board mak ing sure that they are correctly polarized 1 e red to positive and black to negative Clip off all excess wire neatly making sure that all of the soldered connections are properly made Finally check all components to ensure correct ON OFF SWITCH a 9 VOLT BATTERY LL 0T Fig 2 This diagram should make construction and component orientation a snap If so desired a jac
131. aring but not during opera Fig 7 The template for the front panel may be lifted from the page with contact transfer film or it can be copied on acetate by a photo shop and glued to a small piece of Plexiglas This bezel is needed to produce the desired effect tion Set the minutes first 10 of minutes next then the hours using the 3 time set switches No problems should be in curred in accomplishing this To change from BEFORE to AFTER step the min utes past the hour To change from AFTER to BE FORE step the minutes past the half hour As a novelty this clock is a unique addition to any mantle and is sure to be a conversation piece E PARTS LIST FOR THE BEFORE AND AFTER CLOCK SEMICONDUCTORS BR1 1 A 50 PIV fullwave bridge rectifier Radio Shack No 276 1161 or similar D1 D4 1N914 silicon diode D5 D6 1N34 germanium diode DIS1 DIS4 Seven segment common cathode LED display FND 503 or Radio Shack 276 1647 Q1 Q5 2N2222 NPN general purpose silicon tran sistor U1 U3 4511B BCD to 7 segment latch decoder driv er integrated circuit U4 U6 4510B presettable up down counter inte grated circuit U7 4072B dual four input or gate integrated circuit UB U11 U17 4049B hex buffer converter integrated circuit U9 U12 U16 4012B dual four input NAND gate inte grated circuit U10 U1S 4044B quad three state R S latch integrated circuit U13 4001B quad two
132. att 5 fixed resistor R4 R6 20 Megohm 4 watt 5 fixed resistor R5 4700 ohm 4 watt 5 fixed resistor R7 10 Megohm Y4 watt 5 fixed resistor RV1 470 000 ohm trimmer potentiometer T1 1000 ohm to 8 ohm audio impedance matching transformer TR1 DS548 or 2N2222 NPN silicon transistor ADDITIONAL PARTS AND MATERIALS Printed circuit material enclosure 8 ohm loudspeaker 9 volt transistor radio battery battery snap solder hookup wire etc A complete kit of parts battery not included is available from Dick Smith Electronics P O Box 8021 Redwood City CA 94063 priced at 6 95 When ordering refer to catalog No DSFW2 K 2640 Tel 1 800 332 5373 n 0 o NE tor falls into just the right place so that the tuning knob can be screwed on through the hole in the front panel The perfor mance of the set is only as good as the antenna and ground system to which it s connected For that reason we have shown terminals for both the antenna and ground connections on the front panel The frequency range of your receiver with the 18 turn coil is approximately 11 to 35 MHz By substituting an 80 turn coil the range of the receiver becomes around 6 to 11 MHz Even more turns will reduce the range even further Alternatively you can try changing the variable capacitor to see what bands you can cover While other variable capacitors may not fit in the box or even on the printed circuit y
133. ays time the same way that you say it By Al Plavcan JOVER THE YEARS MANY CLOCK VARIATIONS HAVE BEEN crealed everything from the grandfather type of centuries past to the present day digital devices Well in this article we ll be looking at yet another clock a digital one but with a twist Instead of displaying time in the conventional way t displays time in the manner in which it is spoken 9 O clock 20 before 10 10 after 5 and so on Hence its name the Before and After Clock Aside from this clock s being unusual it also has some practical applications By placing it next to an analog clock it can be used to teach the little ones to tell time It might also prove useful in MIN places such as a radio or TV i station where time is an nounced continually How It Works In the circuit for the Before anc After Clock the 60 Hz clocking signal is picked off the AC line and fed to a squar ing circuit comprised of a sin Fig 1 Block diagram of the Before and After Clock outlining the operation of the circuit The circuit uses a 4 4 digit display which means that the 10 s of hours seven segment readout can display either a one or zero ony gle NAND Schmitt trigger before being sent to the divider chain After being divided that signal is fed to the clock input of the up down counters The counter outputs are then fed to a set of seven segment LED display decoder drivers w
134. broadcasts from other countries listen to amateurs talking to each other and learn Morse code What s more you ll be able to tell every one you made it yourself How It Works Figure 1 is a schematic diagram of the Shortwave Receiver Radio waves of all frequencies are picked up by the antenna and are amplified by TRI The amplified extra long life However there is plenty of room if you wish to place two standard 9 volt transistor radio type batteries in par allel inside the case For longest life alkaline batteries are recommended The sensing devices themselves can be any of a large number of types specifically designed for that purpose In the nor mally closed loop one might find tiny magnetic reed switches buried in or screwed to the window sill or door post which are held closed by a small magnet on the window or door itself If a window or door opens the magnet moves away and the switch opens Alternatively INTEGRATED SHORTWAVE RECEIVER Keep tabs on the world with this budget receiver signals are fed via capacitor C2 to a tuned circuit consisting of Ll and CVI that attenuates much of the lower frequencies The tuned circuit acts like a short circuit to all frequencies except one Varying the tuning capacitor alters the range of fre quencies that are attenuated So as far as 9956 of the signals picked up by the anten na are concerned that is the end of the road Current derived from the RF
135. capacitor CVI Notice that only two of the three terminals are actually used Next solder in TI leav ing the center tap on the 1000 ohm side unconnected bend it up and out of the way or snip it off Connect and solder D1 the signal di ode making sure that its properly polar ized remember that the banded end is the cathode K Then position and solder TRI watch the orientation using a heat sink on the leads to prevent thermal damage Make a coil by winding 18 turns of plastic coated hookup wire around the case of a plastic ballpoint pen or some thing similar and solder the leads to the pads marked LI so that it is parallel with the tuning capacitor The combination of the coil and capacitor form the tuned cir cuit Solder on the battery snap and speaker leads The speaker is not polarized but the battery is so take care to make sure its leads are correctly connected the red positive lead goes to the pad marked and the black lead to the negative pad marked Do not connect the battery Now insert and solder the CMOS integrated circuit ICI in place As that device is static sensitive do not remove it from the special conducting foam packag ing until you are ready to mount it Do nat touch the pins of the IC either carefully remove the foam and place the integraied circuit into the correct mounting holes Neatly clip off the excess wire making sure that all of the soldered connections are pro
136. citor has resistance in series it cannot discharge imme diately So whatever voltage the positive end becomes the negative end must go another 6 volts below that again If the collector of TR1 goes to 1 volt the nega tive end of C must go to around minus 5 volts As the negative end of Cl is connected to the base of TR2 it turns off and it remains in that state while C discharges through R1 the LED and R2 Eventually C1 discharges and TR2 can then turn on via R2 As soon as that hap pens C2 s negative end drops down to 5 volts turning off TR Capacitor C2 eventually discharges allowing TRI to turn on again turning off TR2 That cycle continually repeats as long as power is applied As there is an LED in series with TRI every time TRI turns on the current flowing through it must also flow through the LED Thus it flashes giving us one flash for each cycle A second LED can be connected in series with TR2 s collector giving two flashes per cycle The rate at which flash ing occurs is governed by the value of resistors R2 and R3 and capacitors Cl and C2 Varying the value of any or all of those components will vary the circuit speed Putting It Together Obtain the parts specified in the Parts List there is a low priced kit available Mount the components as shown in the parts placement diagram Fig 2 Place and solder the resistors and capacitors first taking care to observe the capacitors polarity
137. clearly defined cases that is very largely an unknown or at best guesstimated value We can for example nominate the resistance at the center of a half wave dipole Fig 1A as being in the region of 72 ohms while a folded version of the half wave dipole Fig 1B will have four times that impedance or 288 ohms often rounded off to 300 ohms A number of factors can cause minor variations to those values such as the diameter of the elements relative to their length space between folded di pole elements etc A more controversial value is that for the popular quarter wave ground plane Fig 1C For years value has been stated in many popular amateur textbooks that the impedance is approximately half the value of the simple dipole or 36 ohms in fact various values have been quoted between 30 and 36 ohms That figure appears to have been based on a the oretically calculated value for a quarter wave radiator work ing against an infinitely large perfectly conducting ground plane Some of those text books even went so far as to describe matching devices which would match that value to the popu lar 50 ohm coax cable and transmitter load requirements As anyone who has tried to make one of those matching systems work or who has attempted to confirm that 50 ohm value 986t 834 NVT 41 HANDS ON ELECTRONICS A RO CIRCLE 746 ON FREE INFORMATION CARD Here s a view of today s combination SWR meter and antenn
138. clumsy and neither one gives any warning of shifting voltage levels Your first indication of a power supply imbalance could be a strange odor or smoke coming from an integrated circuit The Power Supply Balance Indicator is designed UNREGULATED to be an inexpensive quick fix for that problem Its small circuit board and three LED s can be tucked into a corner of even the most compact power supply and its operation is automatic and adjustment free The only visible part of the Indicator are the three LED s which can be mounted anywhere on the power supply s faceplate The operation of the circuit 1s simple When the positive supply is set to a higher level than the negative the yellow indicator LED will light When the negative supply is set higher than the positive the yellow one LED2 will light When the two supply voltage levels are within 1 of each other both LEDI and LED glow indicat Fig 1 The schematic of the Power Supply Balance indicator As you can see there is very little to the circuit Also note that the schematic diagram specifies 28 000 ohm resistors for R1 R3 If those values are not readily available simply measure several 27 000 ohm 5 units until you come up with the necessary values UNREGULATED g 17 35V IN ing a balanced output If either one differs from the other by more than 10 a red wARN light emitting diode LED3 will light to tell you there s potential trouble Ho
139. cts and we ll show you how Amplifiers are one of the most common of all electronic circuits every piece of communication and entertainment equip ment has at least one But they all work in much the same way taking a very small electrical signal one too small to be of much use and adding power to it to pro duce a much larger signal Well the Sim ple Amplifier can be made at a relatively low cost and still prove more useful than its price indicates How It Works RV1 the voLUME control see Fig 1 selects a certain proportion of the applied audio signal to be amplified Capacitors Cl and C2 do not impede the audio signal R1 R4 10K 22k amp TR 8 OHM SPEAKER DS548 a INPUT bendi Fig 1 In the Amplifier circuit RV1 is used as a volume control That component allows you to adjust the amount of signal presented to the amplifier thus you can raise or lower the volume at will enough to drive a loudspeaker They can be regarded as preamplifiers The varying output current of TR2 must pass through the primary winding of TI A varying voltage is hence induced in They are merely DC blocking capacitors which prevent any direct current flowing through the potentiometer from entering the audio circuit TRI and TR2 amplify the audio level significantly but not 9861 833 NVF ao e HANDS ON ELECTRONICS o o the secondary of Tl which as you may have noticed is split in half Two
140. cts just for fun Builders C Please send Please print Name Street Address T City State NEW IDEAS Circuits for Experimenters and Project C Please send one copy of NEW IDEAS at 3 50 First Class postage and handling 1 00 U S and Canada only All other countries 2 00 for sea mail 3 00 for air mail copies of New Ideas Total cost is sum of copy price and First Class postage and handling cost multiplied by number of issues ordered Allow 6 8 weeks for the material to arrive Detach and mail today HANDS ON ELECTRONICS Reprint Department 200 Park Avenue South New York NY 10003 All Payment must be in U S Funds Zip Lemme meee ee eee PRINTED CIRCUITS PRINTED circuit boards TORCCC Electronics will print any schematic 6 by 9 maxium on a circuit board for 1 50 Larger circuits add 1 25 per additional 50 square inches Send check and sche Pel ORCC Ge 2161 North California Chicago 47 REEL TO REEL TAPES AMPEX professional series open reel tape 1800 or 2400 feet on 7 inch reels used once Case of 40 45 00 10 2 x 3600 feet and cassettes avail able MasterCard Visa VALTECH ELECTRONICS Box 6 HE Richboro PA 18954 215 322 4866 CLASSIFIED AD ORDER FORM To run your own classified ad put one word on each of the lines below and send this form along with your check to Hands on Electronics Classified Ads 200 Park Avenue South N Y N Y 10003
141. cuit to be mounted without the use of hardware The external power socket is a good idea particularly if you have a se rious security usage in mind While it will operate for a reasonable time on the 9 volt transistor radio battery an external supply is a much better proposition even if it is only a much larger battery The Siren 1s shown with a small 8 ohm speaker which makes enough noise to drive anyone mad However if you are using the Siren in an application where a lot of noise is needed in an alarm for example you would be much better off replacing the small 8 ohm speaker with a horn speaker Horn speakers are highly efficient compared to the normal type A further modification you may care to make involves replacing the switch If you are uSing the Siren in conjunction with an alarm of some sort the contacts of the PARTS LIST FOR THE ELECTRONIC SIREN ADDITIONAL PARTS AND MATERIALS Printed circuit materials enclosure 9 voit transistor type battery or other 9 volt DC source hook up wire solder switch etc R1 R2 10 000 ohm watt 5 fixed resistor R3 100 000 ohm watt 5 fixed resistor R4 4 7 ohm 1 watt 5 fixed resistor SPKR1 8 ohm loudspeaker TR1 BD140 or ECG 185 PNP silicon transistor alarm relay can be used to switch the Siren on Simply remove the switch and con nect the normally open relay contacts Obviously there are a host of other uses not involving securi
142. cuits are automatically circumvented by the Mark III during all test and run functions During the test function all flyback secondary output is limited to approx 809 of normal 2nd anode voltage is limited to ap prox 5 KV This means all circuits that are not shorted will have some 80 of th t normal B voltage during the test phase It also means thai any shorted circuit will have zero DC volts on it This feature makes any short easy to isoijate The MARK III sells for only 595 Visa and Mastercharge Welcome Diehl Engineering 6661 Canyon Drive F Amarillo TX 7911C Phone 806 359 0329 or 806 359 1824 HV CIRCUIT ANALYST Checks the horiz output stage for opens shorts Checks flyback yoke PC and HV mult Checks all scan derived B sources Checks for open safety capacitors Checks for open ground path for horiz output stage Checks for open primary LV supply Checks for error in interface connections Checks for proper LV regulation Checks for proper start up circuit operation Checks for shorted horiz driver transistor Checks the operation of the horiz osc driver circuits Checks B run supply for the horiz osc driver circuits Checks all circuits in the TV set that rely on scan derived B Automatically circumvents all start up circuits and horiz drive related shut down circuits x x HOOK UP Identical to Mark III OPERATION Turn the Mark V on turn the TV set on
143. d readouts were mounted directly on the circuit board for simplicity but could easily be remotely located by wiring between components and board The readouts are modulated with a 50 duty cycle squarewave to reduce the current drain of the read outs to a level that makes battery operation feasible S3 J GAME Fig 1 The Digital Cribbage Board o START is made up two identical circuits that share only one common component C4 therefore only nd 4 one half of the circuit is shown The circuit s low power CMOS DUAL UP COUNTER The Circuit The input pulses from the count pushbutton switch S1 are conditioned by a debounce circuit consisting of U6 d of a hex Schmitt trigger and fed to the pin 9 inputs of two CD4518 dual up counters U2 and U8 Both U2 and U8 are configured so that one of its internal counters counts units while the other serves as a decade tens counter After a count of ten the units counters of U8 and U2 feed one pulse into their respective decade counters via AND gates U5 a and bid Sunt DiS DIS 5 HP50 2 7653 R7 R36 Ug CD4511 DECODER DRIVER CD4518 OECODER DRIVER U4 a D4013 D TYPE FLIP FLOP construction makes battery 12 joe operation practical 14 X Ay C4 U6 d 100 R3 iL on 1 6 CD4554 U2 CD4518 DUAL C2 UP COUNTER d O 05 COUNT 9 1 8 CD4511 DECOODER L DRIVER Ps O O 8 RESET U6 e E E S2 R4 z 1 6 CD4584
144. d U2 another display decoder driver That decoder driver s output feeds the 10 s of minutes display DIS2 The decoding neces sary to control the up down counting is tapped off the Q outputs of U4 and US and processed through U11 U12 and Ul4 When the Q outputs of U4 pins 6 11 14 2 are all low their inverted outputs through U11 is fed to U12 a All high DIS HOURS g ojj R15 12V 13 12110 9 16 aq L3 m 13 2 40128 4 a stu 2 16r L4 U17 c 14 1 6 4049 i 12V 15 T 71 3 5 8 L 79 COMMDN 10 1 SET U22 PIN 14 12V 02 2N2222 R15 R21 rj inputs to U12 a cause pin 13 of U12 a to go low That s the zero decode for minutes Pins 8 and 9 of U14 d go to US pin 11 and US pin 6 respectively When those two pins are high at the count of 3 pin 10 of U14 d goes low That is the 10 s ot minutes decode of 3 Thus pin 13 of Ul3 a is low zero decode and pin 10 of U14 d is low 10 s of minutes decode of 3 Those signals are now fed to U14 c pins and 2 through inverters U11 e and U11 f U14 c pins and 2 are now high causing pin 3 to go low That point is the 30 minute decode Several things happen at this time First Q2 is turned on through U17 c causing I2 to light showing 30 on the front panel DIS 4 10 S OF HOURS aa as Ces B C 2N2222 gt ix 12V UB8 e 1 6 4049 9861 834 NVfl a m TO U19 PIN
145. d back to provide the input to the first stage When the first stage is saturated it serves to cut off the second stage and vice versa With all the circuit elements the same value the operation of the multivibrator will be sym metrical equal intervals The RF oscillator is controlled by the processor U1 to be discussed shortly using two inverters U4 e and U4 f that are connected to the multivibrator inputs U4 a through U4 d The RF oscillator is disabled when the processor outputs a logic high on its output Port 2 pin 38 to input B in Fig 1 The RF oscillator is coupled to the AC power line using a Sprague pulse transformer T2 and capacitor C3 It is that 120 kHz frequency superimposed onto the AC power lines occurring at the right time in the correct format of on off cycles that contro the BSR remote control modules The right time is established when the signal is transmitted within 100 200 microseconds after zero cross is detected Zero cross occurs when the AC signal crosses its average DC level That synchronization is provided as an input to the processor via transistor Ql circuitry shown in Fig 2 An active low signal signifies a zero cross of the AC line voltage The transmit format required see Fig 3 is a bit more involved There exist two types of operations You can talk to remote contro modules individually or address specific remote D2 1N4148 117 VAC D3 1N4148 D4 1N4001 C1 2200 D5
146. d gates that is rarely done anymore The inte grated circuit manufacturers have already constructed binary counters in a variety of configurations usually in multiples of four or eight bits Different TTL CMOS and ECL integrated circuit s are available depending upon the features included such as presetting down counting etc A Typical IC Counter One of the most used IC counters is the 4 bit MSI device shown in Fig 9 The device is a 4 bit binary up or down counter with presetting In other words it incorporates all of the features that we discussed previously The counter has four outputs which are monitored to determine the number stored in the counter Four parallel data input lines are used for applying a preset input The load input line causes the parallel binary word applied to the data inputs to be loaded into the flip flops The counter also has a clear input line used for resetting the counter to zero 192 L192 L S192 13 BORROW OUTPUT TELA mne AF 2A CARRY OUTPUT DATA i15 Esme LINPUT A m en Ex nb ee eS eS DOWN 4 3 COUNT g i l dl OUTPUT Oa S or DELI COUNT DATA Ui HL TES INPUT B TET Er 12 OUTPUT Og GG ta para t lD E a i6 OUTPUT Qc AM UT INPUT D to 4 CLEAR a gt o 7 OUTPUT Oo LOAD inm gt Fig 8 A 4 bit binary up down counter When the count control signal is high 1 the circuit is an up counter When the count control signal is l
147. d in the timing waveforms of Fig 7 Those output waveforms are the ones that occur at the normal flip flop outputs Since the complement flip flop outputs are not shown it is more diffi cult to trace the operation of that counter If you d like to see how each input pulse causes the toggling and triggering of each flip flop in sequence simply draw the complement signals to each of the waveforms in Fig 7 before doing a pulse by pulse analysis Keep in mind that a down counter can also include preset circuitry so that the counter may begin decrementing at some particular point By adding some logic circuitry to the counter you can make it count either up or down That is illustrated in Fig 8 An up down COUNT CONTROL line is added to determine the direction of count If a binary is applied to that input the counter will count up That binary enables all of the A gates It causes the normal flip flop outputs to pass through the gates to the clock t inputs of the next flip flop in sequence The B gates are inhibited at that time by inverter 1 Fig 7 Down counter s input and output waveforms 9861 g83H NVTl o d INPUT COUNT CONTROL If the up down control line is made binary O the B gates are enabled by inverter and the A gates are inhibited That causes the complement outputs to be passed through to the clock inputs The counter then counts down While binary counters can easily be made up of individual flip flops an
148. d now another first The Fluke 80TK K type Thermocouple Converter A tempera ture measurement device that adds instant temperature measurement capabilities to the 70 Series DMMs Or any DMM for that matter Feature for feature the versatile 80TK is the most affordable unit of its kind For quick comparison readings it can measure C or F at the flick of a switch It includes a built in battery test And the availability of 3 Fluke Drobes give you the flexibility to measure any form of temperature from freezer to turnace with Just one base unit No other thermocouple converter we know of offers DMM users so much for so little Just 59 including a general purpose bead probe So even if you don t own a Fluke 70 Series multimeter the 80TK will help the DMM youre now using measure up when things gel hot Or cold For your nearest distributor call toll free 1 800 227 3800 ext 229 day or night Outside the U S call 1 402 496 1350 ext 229 FROM THE WORLD LEADER IN DIGITAL MULTIMETERS Surface immersion and general purpose probes with mini thermocouple connectors aie avaliable for the Fluke 80TK 80TK SPECIFICATIONS Temperature Measurement Range 50 to 1000 C 58 to 1832 F Battery Life 1600 Hours 9Y FLUKE IN THE U S AND ae EUROPEAN COUNTRIES Jonn Fiuke Mtg Co inc PO Box C9090 M S 250C Everett WA 98206 Sales 206 356 sine ppt 206 347 6100 UROPEAN HEADQUARTERS
149. d to complete the project The only component that s not mirrored in each half of the circuit is C4 which is a filter that is common to both halves The dashed lines indicate jumper connections that are located under compo nents flu vid lL f TE J NNI Im U2 U3 f iti CH l aly J E cHu i QC8u j modulates the seven segment readouts reducing the current drain of the readouts by about 50 Display DIS3 was not modulated because it only illuminates two segments on TOTAL BON ee counts over one hundred Construction In order to lay out the circuit on a single sided printed circuit board many wire jumpers were used Double sided board with plated through holes would simplify and speed construction but the cost of double sided boards make wire jumpers more economically desirable You may make your own board from the foil pattern shown in Fig 2 or purchase SINIOd IWLOL the etched tinned and drilled board from the supplier given COUNT CLEAR RESET PORNO k in the Parts List m Figure 3 gives the location of the components on the printed circuit board Note that the layout is divided in half by a dashed line Each half is identical therefore component designations are duplicated on each half of the board and that condition is reflected in the Parts List where the parts given are only for half the board When purchasing
150. damaged if the system has not been assembled properly Therefore U4 should be in stalled only after a quick test is made to determine that the parts have been installed correctly and that the system is functioning properly Construction Checkout It is important that you verify that the breadboard was assembled correctly and is functioning properly To run the construction checkout the Telephone Remote Control Sys tem software 1f purchased has a built in diagnostic test that is performed prior to connecting the unit to the telephone lines This test uses the Telephone Remote Control System and existing wall switches and lamp modules If your BSR system does not have either of the modules then proceed to Single Multiple Installation Checkout Otherwise perform the following procedure l Set Control System and wall switch module to the same house code 2 Insert the plug of the Control System s AC power cord into a 117 volt AC outlet 3 Verify the light s connected to the aforementioned module s turn on for approximately second and then goes off If not check the following a Module installation is correct b The module house code selected is the same as the Control System s house code selection c The circuit breaker that provides power to the module IS on d Verify that all circuit board components have been installed correctly e Verify 5 volts power on UI pin 40 Since most homes are powered from two 117 volt
151. der during its half INPUT SOCKET cycle that arrangement is much more efficient than using a single transistor to do the same job Thus the output power of that type of circuit is greater than that of a single transistor circuit Capacitor C5 is connected between the two transistors to minimize distortion which can occur as one transistor turns off and the other turns on Both TR3 and TR4 are connected to the positive supply via half the winding of T2 so the current flowing through them must also flow through the transformer Unlike Tl where two out of phase cur rents were induced in the transformer from a single input signal T2 induces a single output current in its secondary from two out of phase currents in its pri mary That output is enough to drive a loudspeaker This type of circuit is called a push pull amplifier as in the first half cycle one transistor pushes then in the second half cycle the other pulls Putting It Together Aj rE 1 AIC K YER TR4 HIS TR2 Beo plifier is to obtain a printed circuit board and the necessary parts The board may be purchased from the supplier given in the Parts List or you can make your own However if desired perforated con struction or experimenter s board may be used Assuming that you have purchased the kit mount and solder the components i shown in Fig 2 the parts placement di agram resistors and capacitors first tak ing great c
152. duce the charac teristic hee haw sound The oscillator based on IC2 is responsible for producing the sound Its output is connected to the base of TR1 which amplifies it to drive the speaker Resistor R4 is included in the circuit to limit the current through TRI to a safe and reasonable level The oscillation frequency of IC2 is par tially dependent on values of R3 and C2 change either one s value and IC2 s output frequency also changes Another factor that governs the frequency of oscillation is the magnitude of voltage fed to pin 5 of IC2 If a voltage of varying magnitude is fed to pin 5 the internal circuitry of the IC is forced to reset at a different rate chang ing the frequency Fig 1 The heart of Siren circuit consists of two 555 timer oscillators with one controlling the 2 other to get the desired 6 affect IC is also connected as an oscillator but it runs much slower than IC2 around 1 Hz Each time the IC triggers the voltage at pin 3 goes high As pin 3 is connected to pin 5 of IC2 this forces IC2 to change its note That gives the hee haw sound of the Siren Later we ll show a couple of ways to change the sound produced by the oscillator if you want to do some experi menting Q Swi F pen HORN 19V 12V SPEAKER BATTERY R3 TRI 3 F 16V T 9861 G34 NVC c HANDS ON ELECTRONICS o o Construction First you l
153. e circuit to work the first time out releasing the button at a certain time to obtain a certain number Increasing the value of R1 and or CI will causes the speed to slow down due to the longer charging time required Wired as a flashing broach with C1 now valued at 3 3 uF and a jumper across switch PBl the LED s will flash slowly in se quence as long as the battery is connected Putting It Together The first thing that you ll need is to obtain a printed circuit board and compo nents in the values given in the Parts List You may choose to make your own board and then go hunting for the parts or order a complete kit from the supplier given in the Parts List PB1 Momentary contact pushbutton switch IC1 555 timer oscillator integrated circuit C2 4017 decade counter CMOS integrated circuit TR1 DS548 2N2222 or similar NPN transistor H1 22 000 ohm V4 watt 5 fixed resistor R2 220 000 ohm watt 5 fixed resistor solder etc R3 1000 ohm 4 watt 5 fixed resistor ADDITIONAL PARTS AND MATERIALS Printed circuit material 9 volt transistor battery or some other DC power supply battery snap hook up wire Fig 2 The printed circuit components installed and example you should have C1 022 uF ceramic or polyester capacitor dice For jewelry use 3 3 u F 10 WVDC electrolytic not supplied in basic kit C2 33 F 10 WVDC electrolytic capacitor A complete Electronic Dice kit not i
154. e PCB Moun Z2259P ND 9 22895 ND E 22815P ND 15 22515S ND 15 22825F ND 25 2282559 ND 25 22837 ND 37 2283 E ND x Wire Wrap 359P sD 3S9 2 3S16F 4D 3516S 4D JS25P AD 35253 WD 3537P 4D 3837S 4D Bridge Rectifiers DIGI KEY 2x Part No F300 ND F30 ND F302 ND F303 ND F304 ND F305 ND F306 ND F307 ND F308 ND F309 ND F310 ND F31 ND F312 ND F313 ND F3 ND F315 ND F316 ND F31 ND F3JB ND F319 ND F320 ND F321 ND F322 ND F323 ND F324 ND F3125 ND F326 ND F327 ND F378 ND F329 ND F3X ND F331 ND F332 ND F333 ND F334 ND F335 ND F336 amp D F337 ND F338 ND F339 ND F340 ND F3A ND Male Male Male Femaia Maie Fomaie N aie Femaie Male Farah Atg v 9 1 to 7 Amp 50 to 400 Volts Maz Max DC AMS Output Input 275 C 35 70 Ma PIV Lag 50 100 200 Olgi Key Pari No RB81351 ND R8152 ND R8153 ND RB154 ND BR805D ND BR8 D ND BRR2D ND BR85D ND R549 ND AS ND R5403 ND RS40A NI ARGOS NC BR6 ND BR ND BAS ND MBBOS ND MBB ND MBB ND MBB NO vwB1005 NO VB Y ND MBY 2 NU MB 103 ND BR1505 ND BR15 ND BRIS KO BR154 ND gR2505 ND BR25 ND BR257 ND 3R254 ND 143 183 32 185 32 ms hat 1534 22358 284 16 100 03 271 bY 311 68 37155 3165 363 6 4311 360 20 Y O x0 00 0 EAN nui OCC e Description Splice tor Spic Retemion Chw 2 930 Male Female Maw Femals Mate Fumale Rrinnton Chip for iotension Ghp 1
155. e lead to the car battery s positive terminal or other convenient 12 volt source and the negative lead to the car s chassis assuming a negative ground vehi cle Unless your car battery s charge is pretty low it won t hurt to leave the LED flashing all the time Darkroom Warning Indicator This cir cuit makes a great little warning for darkrooms etc with the flashing LED meaning stay out Because it might be inconvenient to change batteries all the time you may wish to power the circuit from a plug in battery eliminator wall mounted DC power supply Figure 3 shows full connection details Fig 2 The printed circuit board can be made with one LED as shown or twin LED s see text The printed circuit board can also be cut into a circular shape allowing it to be worn as a brooch badge or pendant Fig 3 The diagrams illustrate how to add an on off switch or a socket for an external wall mounted DC power supply to your projects The same wiring can be used for almost any battered powered project In a a 9 volt snap on battery connector is shown without a switch The solid black lead is negative in all cases b shows how to add an on off switch The red lead or positive is broken by the switch only the center and one of the outside terminals are used In c an 3 5 mm socket re places the switch The socket auto matically cuts off the battery if wired as shown The wiring scheme in d all
156. e right if the battery is reversed The positive red lead goes to the end of the printed circuit board with the LED on it the negative black lead goes to the end with the transistors on it The printed circuit board has been designed to accom modate two LED s but at the moment we need only one Thus a link mentioned earlier made from a short length of cut component lead is used to jumper out the extra LED position Go over the board checking all compo nents battery connections etc If you re satisfied that everything is correct con nect the battery and the LED should start to flash immediately If it doesn t dis connect the battery and recheck every thing component soldered joint and wire It may be that your battery is dead Putting It to Good Use A circuit such as this has several uses 3 12 VDC 3 12 VDC One use for this type of circuit is as an alarm indicator let s say for your car You ve probably seen those rather expen sive auto alarms systems with a flashing lights to warn thieves away This flashing LED can be used for exactly the same purpose and you don t even have to have an alarm You might consider combining this project and a Car Alarm to produce a complete system When connecting the circuit to your auto s electrical sytem no circuit modi fications are needed for 12 volt operation because this circuit is designed to operate over a wide voltage range Just wire the positiv
157. e switches use the tip of a ballpoint pen Push them up to turn them ON and down to turn them OFF The four switches closest to U6 select one of the 16 possible house codes Their settings are used to represent house code letters A through P as shown in Table 1 The three switches closest to K1 select one of the eight possible access codes Their settings represent different ac cess codes as shown in Table 2 More About the Access Codes The access code is actually a 2 digit number The first number is already programmed into your Control System and is always the number 2 The second number you must pro gram Carefully select a number that wil not normally inter fere with local numbers or exchanges frequently dialed If you decide to change your access code follow the procedure below l Disconnect the plug of the Control System s AC power cord from the 117 volt AC outlet 2 Select your new access code 3 Insert the plug of the Control System s AC power cord into a 117 volt AC outlet More About the House Codes There are sixteen house codes to choose from The letters A through P are used The house code selected on the Control System and the remote control modules must be the same For instance if the Control System s house code is set to A then all the remote control modules must have their house code selectors set to A in order to receive the control signals transmitted from the Control System If you decide to change y
158. e upper end of the AM band with the engine run ning and the Monitor operating There should be no interference when the above capacitors are added Learn by Degree In your Letter Box column in the Sum mer 1985 issue of Hands on Electronics you offered advice to an individual who was interested in obtaining an elec tronics engineering degree through home study While your answer did fit the question think it could be improved upon The University of the State of New Continued on page 16 cts Hook it up to your stereo Here s a ton of fun Hide h Cat K 2668 and it can warn you of dam the cricket when the lights lains that it is looking after 49 5 gerous overioads Looks Qo out it starts chirping the car It s actually doing FUN WAY ONE pretty nifty too the LEDs Turn the lights onor make a Much more makes a great light posae music noise and it stops Makes it lights on warning and VALUE PACK Bren ot 2637 895 so hard to find It really is door open warning as well r infuriating as a pseudo burgiar alarm Projects 14 20 Cat K 2663 95 Cat K 2660 Contains the more POE Speciale componens f a required to complete the Morse Two UD Mini Synth last ten projects 11 C d z es Lil PO Ld eed ue pide idc Fun Ue n live must synthe ote you w 0 e Trainer is se as the 1 70 kit above to kits inthe 4 ohis the Miniature Ad as a bonus t
159. e used to lift the patterns directly from the page It s also a good idea to add markers to the film to ensure accurate alignment PC board foils 9861 8ad4 NVC ds TO COMMON 10 S MIN MINUTE S2 HANDS ON ELECTRONICS ao e veeoneeoisnan i Ae SUSAN BOD BOCES TOILET manne iS T L T ABATE Aa NANI A xum wort consent opp AEAEE ope ton EERIE wives ie SSSR i BONN SPURS SUSE EES ALMA GONRICER Soh ih ARES Goat pae DE LOPE EORI ETORRI PID E z AIEEE DOA RI POPETI EIDAPERE Bos cane setts oo eapite nS LO cp sone go BERLE GIR PEL EDIE LOL OL oC vv ree X 4 HOURS SET TO COMMON SET U21 PINS 1 AND 6 Fig 6 Parts layout for the Clock circuit s double sided board Note that all IC s with the exception of the top four have their U shaped notch facing the top of the card Pay strict attention to the orientation of IC s diodes transistors and any other polarized component Also note that the power supply components are not included on this board You may be wondering why the clocking signal is being picked off prior to rectification Consider that the AC line frequency is 60 Hz and that the bridge rectifier puts out a positive going pulse during both the positive and negative transition of the input wave That means that when the input is positive a positive going wave appears at the output and when the input goes negative the bridge outputs a p
160. e waveforms in Fig 1l as a guide While it is possible to construct a BCD flip flop from individual gates and flip flops normally circuits such as that are available as a single MSI integrated circuit Most of those devices feature a master clear or reset line and many of them feature both presetting as well as up and down counting capabilities To use a BCD counter for counting to values higher than 9 all you do is cascade them as shown in Fig 13 The first or input BCD counter then counts in units of 0 through 9 After ten input pulses occur the MSB output of the first counter D triggers the next BCD counter in sequence That second counter represents the tens position It will be incremented for every ten input pulses The tens counter in turn drives the third or hundreds counter It will be incremented each time one hundred input pulses occur Additional counters can be added for thousands tens of thousands hundreds of thou sands and so on To read the content of the counter you observe the BCD codes at the counter outputs For example the number stored in the counter shown is 853 Note that in reading the output of a BCD counter the 4 bit groups are separated from one another The outputs do not form a continuous 12 bit binary number The output is three 4 bit BCD numbers 1000 010 0011 Just as you can use binary counters for frequency division so can you use BCD counters for that application The circuit MDST SIGNIFICAN
161. eady obtained is enough to identify the IC in the data books The alert electronics experimenter uses all the clues he can get using the test equipment he has on hand But when there aren t any advance clues when there is no PC board or when there are no partial markings to go by then the only alternative you have to go on is the C signature WHAT MAKES THE IC SIGNATURE POSSIBLE Practically all IC outputs linear or digital are formed from transistor collectors All NPN collectors are embed ded in a P type substrate that is designated graund V for linear IC s As shown in the accompanying diagram the collector substrate forms a PN junction that lixe any other BASE B Pr COLLECTOR E O m of m Ei F SUBSTRATE V diode conducts well in one direction and poorly in the other Connecting an ohmmeter from substrate to collector in the forward direction positive lead to substrate will cause the ohmmeter to indicate between 500 and 900 ohms Other diodes in the same IC will read between 950 and 1300 ohms Actual resistance values will vary with the type of ohmmeter and the degree of doping in the IC but the IC outputs will always give the lowest readings Thus it is possible to locate every output terminal on an IC The row containing all those low resistance readings will be the ground V row In every IC there are usually several transistors whose collectors are connected to V either direc
162. ectly Power Supply Balance Indicator the test bench designers t ool Identifying unknown IC s page 32 IE 0 om SPECIAL COLUMNS Saxon on Scanners some good news and some bad news Jensen on DX ing Listen to the lands of the tango cumbia mariachi and huayno Friedman on Computers what a hard disk system can do for your personal computer DEPARTMENTS Editorial you re eyeballing a collector s item Letter Box we get letters New Product Showcase consumer goodies we all can use Bookshelf from tomes to catalogs 9861 g34d NVf kh HANDS ON ELECTRONICS NO EDITORIAL PAGE Volume 3 No 1 The ete a the Se rons Activist Be tt You re eyeballing a collector s item It s a new year for Hands on Electronics and we re bringing to our readers a more exciting magazine Let me tell you about some of the highlights The people at Dick Smith Electronics cooperated with the editors of Hands on Electronics in the generation of a special 16 page construction section in this issue The projects presented are some of the most often requested by builders of the editors and Dick Smith Electronics We put them all together in one special section All project parts are available in kit form making the building experience enjoyable and brief Turn to page 53 In this issue you find the first of a series of FactCards prepared for the project builder They are located right after pa
163. edge of the LED itself is cut to 4 of an inch The long lead the one adjacent to the flat edge is cut to a 4 inch Then cut one lead of a Va watt 15 000 ohm resistor to a 1 4 inch and tack solder the resistor to the LED s 74 inch lead Cut the other resistor lead to a quarter of an inch after the soldering You ll need the extra lead length to hold the resistor in position when soldering Now cut a length of salvaged modular telephone wire to about 12 inches strip off the outer insulation on one end to three quarters of an inch and clip off the black and yellow wires at the insulation Strip a quarter of an inch of insulation from the red lead and tin coat with solder the bare wire Cut the green lead to 74 of an inch and strip away a inch of insulation PARTS LIST FOR THE QUICKY TELEPHONE LINE TESTER LED1 Tri color light emitting diode Radio Shack 276 035 or similar Ri 15 000 ohm V4 watt 10 resistor Modular cable plastic tubing solder etc Next slip a 2 inch length of inch diameter clear plastic tubing which costs about 12 cents per foot at local hardware stores over the wire and push it down and out of the way Tack solder the red wire on the free LED lead directly opposite the body of the resistor and then tack solder the green wire to the resistor and trim If done correctly both wires are insulated from each other by the resistor there should be no need to use tape or spaghetti Finally slide
164. egin or itas at ngg Home Car Alarm very practical You couid use this alarm to protect your home and property Uses any of the normal alarm triggering devices 650 Cat K 2635 any kit dropped the voltage an additional 4 volts and now have a nice hold feature built into the telephone set itself One other fact a Radio Shack 276 1067 works equally well in place of the SK3638 SCR tried both H K Caldwell ID voltage across the line should be a nomi nal 48 volts DC We received several let ters about this teliing that the voltage varied from 41 to 56 volts What good is a standard if you can t deviate Almost Like Remote Control know it s an old problem in basic elec tricity how to wire an upstairs lamp so it can be controlled from a downstairs switch and an upstairs switch want to use the same kind of set up to control a different electrical circuit Can you save me some head knocking ARRA B G Dallas TX Q o LAMP TO AC x LINE Q8 ae SPDT SPOT the circuit think you re looking for Timer Universal I e Eggs too hard Time them with this great little timer it really works set it fora few seconds to 15 minutes R 50 Cat K 2624 5 LED Level Display You can turn this audibie ala
165. ep away from such circuits for safety s sake Of course you should also keep well clear of any power supply or mains wiring in transistor circuits too To build a signal tracer all you need do is make a probe and solder a length of wire to it say around 350 mm or so Solder the other end of the lead to the center pin of a 3 5 mm plug see Fig 5 Another length of wire connects the barrel of the 3 5mm plug to an insulated alligator clip black is the best color but it really doesn t matter Plug the lead into your audio Amplifier see Fig 6 and connect the alligator clip to the negative supply ground of the circuit to be tested Your probe can then be touched onto various points of the cir cuit to see what signal is present any signal will be amplified by the audio am plifier and heard through the speaker Ml HOME AND CAR m ALARM __ Pi mi A burglar alarm can help you save money not only by foiling thieves but through lower insurance premiums CRIME IS ON THE INCREASE CARS ARE stolen and homes are illegally entered The Home and Car Alarm could stop your property from becoming the next target on the list It is extremely easy to build and should prove very reliable It has features found in professional alarm systems cost ing hundreds of dollars The Alarm doesn t have complicated timing circuits and setting procedures like many others What s more it s simple to operate be cause it is controlled
166. er should fail either accidentally or intentionally a battery stand by circuit comes into action so that the Alarm is not disabled Only the legiti mate user can turn it off via the key switch How It Works Power for the circuit shown in Fig is derived from two sources a wall mounted DC power supply and a battery back up should the main supply fail or be tam pered with by an intruder So long as the voltage from the adaptor is equal to or greater than the battery voltage the bat tery is kept isolated by D2 As a diode needs at least 0 6 volts between its anode and cathode to turn on with the anode the more positive it does not allow any cur rent to flow from the battery while the main supply is operational That prolongs battery life When power is turned on via the key switch the circuit is armed No action occurs because the IC shorts out C3 and C4 preventing them from charging The normally closed switches between TRI s base and emitter stop TR from turning on The circuit remains in that state until triggered If one of the normally closed window or door switches open TR im mediately turns on taking the collector voltage to some low level If on the other hand one of the nor mally open switches is closed by an in truder stepping on a pressure mat for example the collector of TRI is con nected directly to the negative supply even though TRI itself remains off In either event the sudden reductio
167. er which the replacement IC operate are critical reference should be made to the appropriate manufacturer s literature before a final replacement choice is made Linear IC Equivalents and Pin Connections published by Bernard Babani Publishing Ltd London England is available from Electronics Technology Today P O Box 240 Massapequa NY 11762 0240 It sells for 12 50 plus 1 00 for postage and handling Powerful Projects with Your Timex Sinclair By Jim Stephens You will find in this book the e db t Rem eae _ How to live with someone whos living with cancer When one person gets Cancer everyone in the Family suffers Nobody knows betier than we do how much help and understanding 1s needed Thats why our service and rehabili tauon programs emphasize the whoie family not just the cancer patient Among our regular services we provide information and guidance to patients and families transport patients to and trom treatment supply home care items and assist patients in their return Lo everyday lite Life is what concerns us The life of cancer panents The lives of their fam ies 50 you can see we are even more than the research organization we are so well known to be NO one faces cancer alone AMERICAN CANCER SOCIETY nicest synopsis of Z80 assembly language published to date The text was prepared especially for hobbyists and experimenters novice or experienced Powerful Projects wi
168. erts or removes a small coil in series with the horizontal deflection yoke When the coil is switched out the horizontal sweep stretches out so that 40 characters per line PROTECTIVE FRONT PANEL CONTROLS This is what the motherboard and all the subassemblies look like when interconnected and ready for installation in the cabinet It might appear to be a rat s nest of wiring but it all slides problem free directly into the cabinet MOTHER BOARD CRT The CRT is supplied factory installed inside the cabinet Notice the small white plastic protector over the CRT s pins To prevent accidental damage to the pins it should not be removed until the instant you re ready for final assembly fills almost the entire screen When the coil is switched in the horizontal sweep is compressed so that 80 characters will fill the screen 40 characters would fill approximately half the screen A tweaking adjustment for the 40 80 coil allows the user to optimize the sweep for his or her computer s specific display Since the number of display lines from a computer can vary between 16 and 25 Heath s HVM 122A monitor also permits the vertical height to be similarly tweaked tor optimum size A front panel VERTICAL SIZE adjustment hidden behind a small door along with the BRIGHTNESS CONTRAST HORI ZONTAL and VERTICAL SYNC controls allows the vertical height to be optimized for a particular computer You can 986 g34 NV
169. escription M 1023 Clock Module only Digi Key switching pane finches PC board swerches nardware and ostrucbons 1190 VAC Transformer tor MA 1023M Buezei lor MA 1023 alarm putnur MA1023M P Band T Lad ta M41020T MA10208 MA1C20K Den numon J 3v 5 500mVV Zee IN SBA tu 3 86V 5 500mw Zener 1182 574 aque 3 9v 5 5 QmW Zener iH 485 aquo 4A 3V 538 500mW Zene IN 484 Foun A 7V 5 500mW Zaner INFSO4 aquy 5 1v 5 SO0mW Zener 1h7514 rune 5 6Y 5 Sitimw Zener 182524 equs 6 OV 5 S00mW Zener 2V 5 s 50mW Zent 6 Bv 5 509mW Zener SV 5 500mW Zen B 2V 55 Ser Zane B 7V 5 WOmW Zener 8 1V 5 SOOmW Zener 10V 5 4 OOmW Zenar 11V 5 500mWVy Zener 189528 equ 12V 5 SOUMW Zener INSE3B aque 13V 5 5O0mW Zener i1 N864B eque 14V 55 50mw Zen 18V 5 500mW Zene 16V b s SDOn We Zener 11 NBS5B fron 12V 5 50n yy Zene 18V B SimW Zener 1ENS67B eus 19V 5 500m vy Zener 20V 8 SOOmW Zener 22V 5 SOOm Zune 24v 5 S00mwW Zoner 25N 5 500 mvvy Zener 27V 5 S00 Ww Zener 28V 5 500 mW Zaner BOY 5 5 SOGMW ewe LEN 728 aqui 33V Sx Spem Ww eren 1 3NBT3B eque e mw 14 14 14 14 14 Cot No M4 1023M MA 1023P HC 1g 18 33 a 33 HC 33 a 1B 33 18 33 33 1K5231B 1NS232B 1K amp 5233B 1N5234R 1N5235B 1N52368 1NS237B 1N5238B 1N5239B 1NS240B 1N5241R 1N62478 3N524J8 JN5234B NB5245B N5248B 152478 TNS248B 1 N824938R 1N5250B 1N5251B 1N5252B 1N5251B 1N52548 1N525586
170. f automatically And if you wish you can build two dice into the same box for games such as Backgammon Monopoly etc D1 T T RU Ld IC1 TIMER f 555 C1 022uF JTHE ELECTRONIC DICE CIRCUIT IS GREAT for those who enjoy the fun and excite ment of casino gambling This article tells you how to wire up one dice or die that is the singular word and two dice dice is a plural word How It Works Refer to Fig 1 When the pushbutton switch PBl1 is pressed power is supplied to C1 via RI Cl gradually charges until a certain voltage is reached causing IC to conduct supplying a pulse to IC2 as it discharges Cl Capacitor C1 then starts to charge again repeating the process The combination of R1 Cl and ICI form a relaxation oscillator every time a pulse occurs the circuit relaxes ready to start over IC2 is a counter which simply detects the pulses supplied by IC and counts them It shows how many pulses it has counted by causing an LED to glow repre senting that number That IC can in fact count to ten however we want it to count up to six So instead of causing an LED to glow on the seventh pulse the pin that would be used for that purpose pin 5 is connected to another pin pin 15 which causes the counter to reset to zero ready to start counting again The counter keeps counting as pulses continue to arrive When the push button is released the oscillator stops and no m
171. flop is added to the binary counter the maximum number of states it can represent doubles Some commonly used counter sizes and the count capability are given below Name of Bits Maximum Maximum Flip Flops States Count While such counters are useful in practice there are many situations where it is more desirable to use a decimal like representation Humans use the decimal number system and are more comfortable with it than with binary In working with electronic equipment it is desirable to enter data in decimal form and read it out in decimal form To ease the man machine communications problem some special binary codes have been developed The most popular of those is binary coded decimal BCD BCD is still a binary code in that decimal values are represented with binary numbers However only the decimal numbers 0 through 9 are used The Fig 9 Schematic diagram for the Texas Instrument HANDS ON ELECTRONICS 74192 4 bit binary up down counter e e iUt O oO o c DECIMAL D BCD code is shown in Fig 10 Decimal numbers are repre sented by 4 bit BCD numbers one for each digit For exam ple the number 729 in BCD is O11 0010 1001 By using flip flops and gates it 1s possible to construct a BCD counter that is one that counts by tens It has ten states 0 through 9 Such a counter is called a BCD counter decimal or decade counter you see one in Fig 11 Notice that the first three flip flops
172. flop to accommodate the new Input bit After four clock pulses have occurred the entire serial word is now contained in the shift register as shown Holding the input line at zero and applying four additional shift pulses will cause the binary number stored in the shift register to be shifted out a bit at a time thereby generating a serial output word The process is illustrated in Fig 16 As you can see the shift register can be used to accept store and generate serial binary data words One of the most common applications for a shift register is serial to parallel data conversion A serial data word can be shifted into the shift register If the outputs of the individual flip flops are available then that word will appear as a paral lel data word as shown in Fig 17A If the flip flops in the shift register have presetting circuitry similar to that described earlier for binary counters then the shift register can be loaded with a parallel binary number Once the shift register is preset with the parallel number shift pulses will shift the word out a bit at a time That creates a serial version of the parallel input word Thus the shift register accomplishes parallel to serial data conversion as that shown in Fig 17B Like counters shift registers are available as prepackaged circuits in a variety of forms MSI devices with four and eight bits are common Those feature preset clear shift right or shift right and left Larger shift
173. g 1 so that a positive DC voltage causes the device to glow green while a negative DC voltage causes a red glow Resistor RI s value must be large enough so that the current produced by the 90 volt AC ringing signal doesn t overload the LED And yet RI s resistance value must be small enough so that the LED glows in response to the 48 volt DC line voltage A 15 000 ohm unit is capable of handling both situations The reason the glow extinguishes when a telephone 1s connected to the line is that the telephone represents a load of approximately 200 250 ohms which causes the line voltage to drop to about 5 volts Part of the reason for RI s 15 000 ohm value is to drop the current to the LED so low at 5 volts DC that the glow is too dim to be seen thereby serving as a test that a telephone has in fact been connected to the telephone line Similarly if you want to check an extension telephone simply connect the tester at one jack and pick up the exten sion phone in the other room The testers glow should extinguish when the extension goes off hook Construction There is absolutely no sense in turning the Quickie Tele phone line Tester into an expensive project by using a fancy cabinet and construction The pocket tester assembly shown in the photos will work just as well as anything else and it will fold neatly into a short pocket it s built that way The shorter lead of the LED the one that s not adjacent to the flat
174. g 4878 3755 326784 8 B RA4IE BND 456 2056 31420 7736408 2B R 418 8ND 537 4 78 3B 50 17320816 2B R amp 4 528ND BSS 36 44020 102K 40816 2B R a p ND 5241 4660 35950 3 7900 R16 Reet 18 ND n 5 0 42 50 357500 His R841 36 ND 6760 51 a4g4 00 B16 44 ERO EEr R5 15 L 5 0 541l 0 24 A51 1A ND 551 HEVE R5 A511 36 ND B 3065 B 28 38B R51 6 ND 800 2986 25 R512 18 ND 657 3259 5 f 26 A512 35 ND 742 3658 24 J R5135 ND 739 3553 5c l2 3 R513 18 ND 813 a010 sc M24 34 R513 36 NO 325 alg 50795 454g ne M74 40 R 14 BNO 870 00 a B 2 s2e50 ze 40 R5 4 1B AD 858 amp 4 2578 a705 0C Moa 40 R514 3b ND 10 89 63820 533500 Box st R55 6 ND 8 35 54626 aBa 5C R2 50 A505 i840 1 95 604 DO 5417 5C 8515 16 40 12 69 9320 62000C R348 B NU 236 2062 1235 00 R328 18 NO 267 2564 1385 00 R328 36 ND 311 2 8 I ro 00 R329 6 ND Jis 2825 1635 00 R329 18 ND 3155 32 1B45 R3 8 38 ND 383 331 1845 R330 B D J 8 3145 141 7 A330 18 ND 435 38 2190 75 A330 36 ND 20 600 2600 2 833 amp ND 467 4135 134 25 AIT 18 AO 542 VJ 2704 75 R331 35 NU E53 527 3238 5 R332 6 WD 551 48 11 214150 A332 18 hU 638 64 AJJ 36 NO 69 6899 R333 6 Sf 632 5568 R333 10 ND 74 555 41990 366 5l R333 ab ND g05 8004 512720 14500 PLE CARD tG t AaTB BAND 407 359 27896 055m A418 18 Nn 480 1984 25246 285 RA18 35 ND S15 4564 28776 SBI R419 BND 481 4768 2691 H1300 8419 1840 538 4760 29974 258700 4459 96 NU 6 554 3456
175. ge 38 Clip these valuable cards and save them More will follow each issue In time your card collection will be an invaluable asset and will find its place on your workbench There are two projects in this issue that are real sleepers They may become the most talked about projects in 1986 They are the Digital Cribbage Board page 23 and Telephone Hemote Control System page 69 In fact you d best hang on to this issue don t lend it to friends The Editor is forecasting a sel out and that includes office copies too OA Julian S Martin KA2GUN Editor Composition and interior design by Cover photography by Mates Graphics Walter Herstatt BUSINESS AND EDITORIAL OFFICES Gernsback Publications Inc Brian C Fenton associate editor De Piety S New York NY 10003 tanh pie Bilge a ka A al Chairman of the Board M Harvey Gernsback Car Laron associate editor President Larry Steckler Ruby M Yee production manager Hugo Gernsback 1884 1967 founder Robert A W Lowndes production NATIONAL ADVERTISING SALES M Harvey Gernsback editor in chief associate For Advertising Inquiries Only Larry Steckler CET publisher Karen S Tucker production assistant Joe Shere i Art Kleiman editorial director Geoffrey S Weil production assistant 1507 Bonnie Doone Terrace Julian S Martin KA2GUN editor Jacqueline P Cheeseboro circulation director Corona Del Mar CA 92625 Robert A Young associate editor Arline R Fishman advertisi
176. h V applied we connect a voltmeter from ground to a terminal thought to be an output Ground the inputs one at a time noting the change if any in the metered output If that output does not change state for any grounded input repeat the procedure this time connecting one input at a time to V instead of ground In this example it happened that pin 3 went low when either pin or pin 2 was pulled high to V None of the other outputs responded to changes in pin I or pin 2 That indicates that pins and 2 are inputs to one gate whose 986 g3d Nvrn 4 HANDS ON ELECTRONICS C2 ios A LOGIC FAMILY TREE Mention is made in this article of the RTL Resistor Transistor Logic DTL Diode Transistor Logic fam ilies Of the three TTL is the only one that is still in common use but a look at its predecessors is worthwhile Refer to Fig 4 As advances in technology have made it possible to construct more complicated devices on a silicon chip we have been able to take advantage of their sophistication to create faster and more elaborate logic families All three of those logic family C s work by causing their output transistors to go into saturation a condition where no amplification takes place only conduction but differ in the way input signals are processed to bring about that state RTL was the first IC logic family to find widespread use Each input line going to the output transistor contains a resistor
177. has a typical switching speed of 25 nanoseconds and requires a four volt supply Finally TTL uses multi emitter transistors in the input stage The base collector junction of those transistors is never fully off meaning that a state of saturation can be reached considerably more quickly than with either RTL or TTL Switching speeds for simple TTL IC s are frequently under 10 nanoseconds TTL uses a five volt supply While it is still possible to find RTL and DTL IC s on the surplus market the TTL family is now the dominant one Its two most common forms are standard TTL and LS Low power Schottky TTL techniques I would have tried exercising two or even three inputs at a time and I would have begun to search for a possible enable or inhibit input The more complicated devices require a little ingenuity and some intelligent guess work Step 7 Use the results of Step 6 to draw the schematic diagram of the IC At that point the device could be used in the average hobby project without needing to know any more about it But if you feel compelled to assign a number to your IC it s time to consult the IC data books That s what I did Step 8 It took quite a while to locate a Motorola IC book con taining RTL data sheets The electronics department at the local college was good enough to let me look through their copy If you need that kind of assistance let me urge that you make the local college your first stop I
178. hat you will want to protect it in a box The PC board Supplied with the kit has been designed to fit into the smallest slotted Zippy box see Fig 4 Dick Smith Cat H 2755 with plenty of room for the battery If that box is used we would assume further that you will want to include an on off switch Once again Figure 3 gives the details Making electronic jewelry A printed cir cuit pattern has been provided that s larger than the circuit board supplied with the kit for those who want to make elec tronic jewelry see Fig 5 The extra size is to allow room behind the main printed circuit for batteries The smaller board isn t big enough Figure 6 shows the printed circuit pattern needed for battery mounting on the electronic jewelry The pattern can be copied and etched You may have noticed that all the tracks on the printed circuit board are crowded into a small circle in the middle of the board Normally that would be taboo and bare board material should be avoid ed Obviously there is a reason for that We have designed the board that way so that the circular pattern can be cut out with a fine hacksaw and filed down al lowing the printed circuit to be used as a brooch or badge Electronic jewelry is all the rage overseas and is now being seen elsewhere However the prices have been very high now you can make your own at a fraction of the cost There are a number of ways you can assemble and wear the circuit Perh
179. he 986 d34 NVf on Nel PROOUbIS SONGS Automatic Digital SWR Wattmeter The MFJ 818 automatic digital SWR wattmeter has bright orange LED digits on the SWR display But more impor tantly this SWR wattmeter is automatic eliminating three steps in reading SWR Switching to set setting the meter needle for full scale deflection and switching back to SWR to read The meter reads SWR L1 to 1 9 9 directly and in stantaneously There is no need to adjust the SWR set knob CIRCLE 728 ON FREE INFORMATION CARD The MFJ 818 reads up to 200 watts of RF output on its LED bargraph display The 12 bar display indicates the on air power level instantly and correctly to show instantaneous peak power The unit to indicate the antenna matching con dition Green for good yellow for not very good and red for a mismatched con dition The MFJ 818 meter which measures only 5 x 4 X l inches carries a one year unconditional warranty and retails tor only 89 95 In addition if you order directly from MFJ you get a 30 day money back guarantee If not completely delighted send the product back within 30 days tor full refund less shipping The MFJ 818 can be charged to your Visa or Mastercard account if you wish to order over the phone Call 800 647 1800 toll free or write to MFJ Enterprises Inc P O Box 494 Mississippi State MS 39762 Locking Leads F
180. he program counter and is connected to the program memory chip addresses A8 AIO Pin 37 is connected to the alarm circuitry and when enabled active low will turn on all remote control light modules Pin 38 is an output and con 5V O 5V 47K O Fig 2 The Control System s printed circuit board is con nected to the telephone line through an opto coupler U6 which provides isolation between the two circuits while allowing them to interact in the manner described see text The cir cuit is controlled by a micro processor which taps into the data stored in EPROM U3 to perform the desired task R16 10K ALARM TERMINALS SHORT CIRCUIT TURNS D6 1N4148 ON AS AS Q R7 47K 2N2222A amp Q2 E 2N2222A 7 R15 43012 R11 4302 trols the RF oscillator The microprocessor U1 ALE and PSEN outputs are con trol lines and are connected to U2 and U3 respectively The ALE line stands for Address Latch Enable and will occur once during each cycle The PSEN line Program Store Enable is an active low signal and occurs during an external program memory fetch instruction The microprocessor Ul has two input lines that can be sampled and action taken via dedicated conditional jump instructions The first of those signals TO is used to detect a SYNC IDENTIFIER H USE CODE Ke M 366 MILLIisec ____ _ gt Fig 3 These block illustrations i
181. he battery compartment and stop conduction between the battery and the printed circuit Another thing that can stop good contact is small breaks in the copper traces we coated tinned both battery boards with solder to prevent the copper from tarnishing which also bridges any gaps in the traces An opposite problem to that is un wanted connections short circuits be tween components of the battery holders The screw head can short onto or between the traces of the printed circuit so we covered the head of the screw with insula tion tape before assembly The nut on the back battery printed circuit board is not soldered to the copper it is glued to blank board to prevent short circuits In our simple flasher we didn t fit an on off switch rather we used the negative lead from the batteries to connect with a small hook soldered to the negative con nection point on the main printed circuit There are other ideas you could try of course A pin clasp glued to the back of the rear printed circuit board which when closed completes the circuit We have barely scratched the surface of this exciting subject the limit is your own imagination This is one way to make a brooch or badge with its own battery supply glued to the back The batteries are sandwiched between two circular printed circuit boards A slot is cut into the boards so that when they are placed together copper facing in with the batteries sandwiched bet
182. he measured resistance across the top row of the signature chart resistance mea surement of over several hundred thousand ohms does not convey very much useful information so there is no need to record it put a dash through the box instead Move the positive lead to pin 2 and fill in the second row of the signature chart Fig 1 by moving the negative lead to pin 1 3 4 etc Continue in the same manner until every row of the signature chart is completed If that is done properly you should have as many rows in your chart as there are IC pins The steps that follow show how to use the completed signature to identify your IC Step 1 Examine the signa ure chart that vou generated from an unknown IC and circle each 2rminal to terminal resistor you can tell which ones those are because each purely re sistive connection between two terminals reads approx imately the same in both directions For the purpose of an explanatory example refer to Fig 2 which illustrates a completed signature chart for an unknown IC n Fig 2 there are twelve circled boxes six above the diagonal and six below The circled number in row 5 column 3 has its mirror image on the opposite side of the diagonal in Row 3 Column 5 The resistance is 7000 ohms in both directions therefore it is a terminal to terminal resistance That fact is noted to the right of the chart Fig 2 along with the other resistance value and identified as Step 1 The re
183. hich drive four LED mod ules The up down counters also contro several lamps that are used to illuminate the other non LED displays Decoding is performed at the hour and half hour to contro the up down counters and light the appropriate display Zero blanking is included to eliminate leading zeros In operation the minutes display advances to a full count 10 S MIN 10 S HRS 986 834d NVP A iS HANDS ON ELECTRONICS amp a of nine then resets to zero and begins to count up again When the minutes display shows a zero the ten s of minutes display lights showing a l as the minutes display continues the count That process is repeated until the count reaches 30 at that time the Clock begins to count down going from 29 to zero At zero the hours display lights showing the hour and the after the hour count begins again until the next hour is decoded The Big Picture Turning to Fig 2 a schematic diagram of the Before and After Clock let s take a look at the overall view of what is really happening in the circuit Timing for the circuit is DIS1 MINUTES R1 D1 D2 12V 10 91 5h14 13 TO COMMON lf SET U22 PIN 14 D 1N914 1N914 1N914 TO COMMON SET U22 PIN 14 derived from the 60 cycle line frequency through a resistor network made up of R36 R37 in the power supply circuit That signal is fed to U19 a hex Schmitt trigger which shears off
184. hich is enabled by the control line That passes through OR SERIAL IN RECIRCULATE 256 BIT SHIFT REGISTER CONTROL BIT COUNTER WORD COUNTER CLOCK BYTE ADDRESS Fig 19 A 256 bit shift register used as a memory bank gate C to the shift register input During that time any new serial data is ignored at gate B which is inhibited by the inverter operated by the CONTROL line To enter new data the CONTROL line is set to binary 0 That enables gate B and inhibits gate A No recirculation will take place However as shift pulses are applied the new serial byte to be stored will be shifted in a bit at a time To keep track of where the different bytes are stored in the shift register memory the circuit in Fig 19 uses a 3 bit binary counter and a 5 bit binary counter The 5 bit binary counter is word counter and its output is a 5 bit binary word we call the address Remember that we said that it is possible to store 32 bytes in a 256 bit shift register We label those bytes byte 0 through byte 31 The 5 bit counter has a maximum count capability of 31 therefore the address appearing at the output of the counter designates which byte appears at the far right of the shift register ready to be shifted out The 3 bit binary counter is used to count clock pulses That 8 state counter counts to eight for each byte stored or read out Recall that it takes eight clock pulses to either shift a byte in or shift a byte out
185. huayno they re no more alike ther Mozart and Madonna What that all means is that when it comes to listening to the shortwave sta tions of Central and South America and their off shore islands there is a tremen dous variety of programming awaiting you Unfortunately beginning shortwave listeners tend to shy away from those sta tions There are hundreds of Latin stations on the bands but compared to most of the powerhouse broadcasters of Europe and Asia most are relatively low powered Signals typically aren t as big and boom ing Also the majority but no means all of those Latin voices operate on the so called Tropical Bands the SW chan Continued on page 102 HCJB CLAYTON HOWAR HELEN HOWARD M elen and Clayton Howard sent this farewell card to many of their listeners when they retired from the staff of HCJB in Quito Ecuador in 1984 Clayton served the station for 43 years Both Howards were familiar to listeners as hosts of the popular DX Party Line program decr Pm 1 8 The Digital Cribbage Board may nol improve your game but it will make scorekeeping quicker and a lot more fan than a board and pegs By W Schopp E rd e ly THE CARD GAME CALLED CRIBBAGE scorekeepine requires a counter sco e keeper that ot only tal ies total poirts buzalso shows the pointceunt of the last olay entered Our Digizal Cribbare Counter fills those requirements andi
186. ial is given for every component used in a particular assembly and each component pictorial is identi fied with an individual identification number exclusive of the conventional Heathkit part number Since the kit contains a goodly number of parts many of which resemble others the individual keying of the components makes for almost goof proof assembly In fact the only problem we had in assembling the unit came about when we thought we knew so much that we didn t have to check the pictorial Sure enough we found that we d used the wrong screws So when it came time for the final assembly we couldn t get the monitor together which meant that we had to go back and find out where we d swapped similar appearing screws Although most of the work is quite easy the illustrations for the final assembly may be misleading which caused our builder to spend more than an hour looking for trouble that didn t exist Firstly there is the installation of the deflection yoke The main pictorials in the illustration booklet show the yoke with with the wrong orientation If you install it the way it appears in the booklet you ll end up with an inverted screen display If you look at the back of the CRT the deflection yoke s wires should stick out the left side to 9 o clock not down and to the right at 4 o clock as shown in the illustration booklet The proper yoke position is shown in the main assembly manual on page 49 The illustration book s pic
187. ics Electronics should be fun but far too often it is presented as a difficult myster ious subject Even books for beginners have not been successful i presented as successful in breaking down this barrier Dick Smith Electronics chang ed all that with the Fun Way Series From the very basics of Fun Way One through to the advanced projects of Fun Way Three electronics is dealt with in a fun way that s really easy to understand amp most of al enjoyable 9RDER TO 75 the Build an Antique Shortwave He ceiver Reinartz 2 that appeared in the Spring 1985 issue of Hands on Elec tronics should shortwave fans be inter ested 5V 15V f LED 1 gt R3 NS 4 8 lt 2 2K R1 4702 3 1c 2 555 68K 6 M LED2 i E Ele CI NS T 1O0QuF TN 10uF i jeg 70 WA Volume 1 Fun Way 1 assumes you know absolutely nothing It will show you what the components look like how to connect them into the circuit even how to go on with further experr f ments with your circuits 5 when they are finished p Cat 95 Volume 2 Fun Way Volume 2 takes over where Fun Way 1 finishes with 20 exciting new projects to try out But these projects are different They re all built 1 the modern way on print ed curcuit boards Which means of course all components are solder position 65 Cat B 260
188. ig Key 19000 63 534 1397 17977 54 i dea exe i5 S E sten IUE Manon 74170N 2 63 f 7451356 CEN 15 ue a3 LM2901N 1 249 D AB334N 350 2N3095 202 1690 15 20 1344 00 1 4 Watt Mets Film Assortments 12 10 8 tha 1283 13 108 i e 9107 1 E 2 MS A e in PD ae d r ANN MEN JAMC2AN 3 10 45288 133 AN i 2 A D amp D A NNS904 3 220 1690 i25 ASKI Soach of vaiues 102 1097 62 22 96 77 10 103170 man 18 116 gsg 2 8 68 50 321 2748 22900 2061 00 1 745 139N puconw Tofas 2 afim E bur B ns We n m v n nn wm uis eum v 2 ts mig mre m TANTON I 745 140N MHCMQON 245 aoziB des qd iH BETIS diei n 2m 19 17875 RSX2 Seacho values 1009 to 9760 2298 100 10 2a 2 00 16 6 y 1 33 1138 P2003 15 5p 686 5680 49000 4810 00 AE 7JAMCIASN 245 as 75 k 7 15 50 178 75 480 total pcs 220 1a b 2 1 595 74177N 120 1N 0 5498 ZOOPLM2R2N 2 449 ADCOBOALCNE 00 2N446 a pc 330 10 33 278 2315 24 1255 assoarwrer or is eoruias CAT NO 7A180N ii siaw 1 BOP 400 8N 3 0 esgan LMN 8 3 208 ADCOBOSLCNS 63 f 28440 23 2 0 890 1M25 mss Sasch of values 1 00KO 109 78KQ 429 4m 10 48 372 39 5 29 ie femurs rawasowc QUALITY E KIT 495 24181N 30 87s17N 150 CHEN 3 55 47238 1 BALM 29 7N 344 ADCOBOBCCN 12 6 2 15 Z RI WA 173 25 480 tota pcs s f iwo o s i8 we on oan 292 SEM 1 15 1 745 158 1 T6 E251N 113 0248 188 29 178 3 2 30 ADCOBOSCCNS 88 pe Ei 3 A 00 247 S MP atn pm M mro 2200 78 53 5528 70 52 a 4 Metallized Pol c d 745 160N 7 4H N 115 i 4
189. ights are now green The scan circuit short detector in the Mark V is identical in all ways to that which is used in the Mark IIl Operation is also identical Both units are virtually indestructable when simple directions are followed Both units carry a full year s warranty against defects in materials and workmanship parts and labor Either unit can be easily repaired by almost any technician in his own shop If the green circuits clear light is now lit It is now safe to push the run button and examine the symptoms that appear on the CRT screen for the purpose of isolating any open cir cuits Except for hook up and CRT filament warm up time this test can easily be completed in two to five seconds The Mark V sells for only 995 Visa and Mastercharge Welcome Diehl Engineering 6661 Canyon Drive F e Amarillo TX 79110 Phone 806 359 0329 or 806 359 1824 EP Sus d MRE AC EOIN re MN RU CM AAA Miis TAE A I STARR AMBAS A BARN S EINE EE EEE ANH HIER ERTIES EEE BEE d 3 prod KIL S ZTO8 7K mc 77h a O wITH Acc Bot pees OPEN Ars e oe 23 ilu fe 4 wr n Y o sn NO LOADS APPEAL sete STOS 7K t S3ro 71kA ERE S io qu od f 5 TO 14 TKA oi nd Y a ries ep ie Einem D i L oed 4 i eee AEN a an PiN 2 penne ia 3 id n 70 X 4 4 450i 1 sibus den deg v p ERA Sere 4 P 4 95 4 3 ael meho ot sass et se cc eek Gl M
190. ing etc Hand held compiete LGUS3 Plans 10 00 Kit amp Assembled Units Available IR PULSED LASER RIFLE Produces 15 30 watt infra red pulses at 200 2000 per sec LRG3 All Parts amp Diodes Available 10 00 BEGINNERS LOW POWER VISIBLE LASER Choice of red yellow green provides an excellent source of monochromatic light LHC2 Plans 5 00 LHC2K SNOOPER PHONE Allows user to cali his premises and listen in without phone ever ringing SNP20 SNP2 Plans 9 00 SNP2K Assembled Kit 34 50 LONG RANGE WIRELESS MIKE Mimature device Clearly transmits well over one mile Super sensitive powerful MFT1 Plans 7 00 MFT1K WIRELESS TELEPHONE TRANSMITTER Transmits both sides of phone conversation over one mile shuts off automatically VWPMS Plans 8 00 VWPMSK Plans Kit TALK amp TELL AUTOMATIC TELEPHONE RECORDING DEVICE Great for monitoring telephone use TAT20 TAT2 Plans T 5 00 TAT2K Our phone is open for orders anytime Technicians are avaiable 9 11 Assembled 89 50 Plans Kit 59 50 Plans Kit 49 50 39 50 24 50 Plans Kt 14 50 a m Mon Thurs for those needing assistance or information Send 1 00 for catalog of hundreds more similar devices Send check cash INFORMATION UNLIMITED DEPT RB P O Bux 716 Amherst N H 03031 Tel 603 673 4730 MO Visa MC COD to Rit wi CAM aer S oS oc mE pe 0 gude 3 eyes CIRCLE 712 ON FREE INF
191. input nor gate integrated circuit U14 4011B quad two input nano gate integrated cir cuit U18 4528B dual monostable multivibrator integrated Circuit U19 4093B quad two input NanD Schmitt trigger inte grated circuit U20 U23 4018B presettable divide by N counter in tegrated circuit U24 LM340 12 or LM7812 positive 12 volt 1 A volt age regulator RESISTORS All resistors 1 4 watt 5 fixed resistors R1 R21 R25 1000 ohm R22 R24 R26 R28 R32 4 700 ohm R30 R34 R35 10 000 ohm R36 100 000 ohm R37 82 000 ohm CAPACITORS C1 C7 1 wF 25 WVDC ceramic disc C8 C9 001 yF 25 WVDC ceramic disc C10 1000 F 35 WVDC electrolytic ADDITIONAL PARTS AND MATERIALS 1 14 12 volt 25 mA incandescent lamps Radio Shack 272 1141 S1 S3 SPDT toggle switch T1 Step down power transformer 117 VAC primary 12 volts 1 A secondary Cabinet hardware printed circuit materials bezel ma terial line cord with molded plug wire solder etc A printed circuit board part No RW501 with plated through holes and reflowed solder for the Before and After Clock is available for 27 00 plus 2 00 postage and handling from Danocinths Inc P O Box 261 West land MI 48185 Please allow 6 to 8 weeks for delivery 9861 834 NVf go Build and checkout this ADJUSTABLE TIMER With just a little imagination this simple timing circuit can be made to control any number of el
192. into control or measurement equipment _ LONG DISTANCE TV DXING 5 00 A practical and authorilative introduction to ths un usual aspect of electronics ELECTRONIC SCI ENCE PROJECTS 5 75 Simple to com plex a group of projects with a strongly scientific flavor J a MM Cubs pinas ODE CHARACTERIS TICS EQUIVS AND SUBS 5 00 Shows tull interchangeabihty data for thousands of di odes ELECTRONIC MU SIC AND CREATIVE TAPE RECORDING 5 00 Shows how you can make electronic mu sic al home with simple and inexpensive equip FIRST BOOK OF DI THE PRE BASIC BOOK Reg SL NOW 55 50 BUILD TREASURE LOCATORS Reg 2M NOW 4 00 AUDIO AMPLIFIER CONSTRUCTION Reg Seem NOW 4 50 AUDIO PROJECTS Reg SIPSILNOW 4 00 GRAMMING THE ATARI 600 800 XL 5 00 Perfect complement to the Atari users manual Even shows how 10 use animated graphics MICRO INTERFAC ING CIRCUITS BOOK 2 5 75 Interfacing Sound and speech gener ators temperature and optical sensors motor controllers and more HOW TO DESIGN ELECTRONIC PROJ ECTS 5 75 How 10 use standard circuit ele ments to make custom electronic projects CRYSTAL SET CON STRUCTION 4 50 A variety of crystal radio receivers for the expert menter and hobbyist MODERN OP AMP PROJECTS 5 00 includes a Slide Timer AF Signal Gen Mike Pre amp scratch Filter and much more _ COUNTER DRIV
193. ip Valid for new members only Foreign applicants will receive ordering instructions Canada must remit in U S currency This order subject to acceptance by the Electronics Book Club RESP 186 Em NEED NEN NEN GN GNE E ENS ee ee ee ee EN ee ee ee U N Phone This will be coming to you when you subscribe to Radio Electronics e HELPFUL CONSTRUCTION ARTICLES Test Equipment Hi Fi Accessories Telephone Accessories Music Synthesizers Computer Equipment Automotive Equipment Intruder Alarms Home amp Car Video Accessories e NEWS ON NEW TECHNOLOGY Computers Microprocessors Satellite TV Teletext Automotive Electronics Speech Synthesizers IC Applications e FASCINATING HOW TO DO IT ARTICLES Build Your Own Projects Make Your Own PC Boards Wiring Techniques Soldering and Desoldering Design and Prototyping SATELLITE TV STEREO With this autema ed LPS SPECIAL SECTION LU etree BUYERS GLHDE COMPUTERS Vie ST FREQ TECHNOL CY SERVICE BUILD THIS ELECTRONICS IN MEDICINE How mages of the human body are produced SATELLITE TV C Quy hd DEMODULATOR R E s add on for your satellite TV rece ver k nes you into stereo cuo I RECHARGEABLE BATTERIES gt Hove to choose ihe one that best Suits your needs BULDA COMPUTERIZED ic TESTER SATELLITE TV COMPONENT BUYERS GUIDE Whats available fs you want to pacc togelher your satelite receiver
194. is for the most part of the textbook variety yet there are a couple of features added for the user s benefit One of those additions light emitting diodes LED s indicate to the user at a glance what the status of the circuit is at any given moment The switches are a second added feature ease of interpretation as shown in Fig 1 You may have other ideas so follow your own dictates As outlined the Adjustable Timer is set up to be built on a solderless breadboard system The physical layout has been aided by use of a solderless breadboard One nice thing about using such a System is that a pre printed paper overlay of the board can be used to map out the circuit making all changes in the layout as necessary Then using that paper version as a template you can transfer your final layout to some form of permanent board if desired Putting It Together A pre etched phenolic circuit board having the same basic pattern as the solderless breadboard and the layout sheet can be used to permanently mount the circuit When parts are Continued on page 103 F ed S Pers i M JS PROJECT PARADE Here are 5 popular projects that are qoof proof Build them tonight and put them to use tomorrow JTHE PROJECTS CONTAINED IN THIS SPECIAL SECTION OF Hands on Electronics have been carefully selected for their universal appeal and many applications in the home office workshop factory in fact anywhere people go
195. is common to C Then turn the board over and carefully solder each of the pins to the pads mak ing sure you don t bridge the pads Inspect the connections to make sure you ve soldered them all without shorting out any of the pads Then do the same for IC pin of IC2 also goes to the negative bus that joins C2 and the collector of TR Connect and solder the speaker wires to the board at the pads marked SPKR and then solder the other ends to the speaker Solder on the batterv snap wires again taking care to see that you have them correctly polarized red positive to the pad marked and black to the negative pad marked Before you connect the battery make certain that all of the components are in the right place correctly oriented and C1 47 4F 25 WVDC electrolytic capacitor C2 0 0047 4 F 25 WVDC polyester capacitor C3 100 uF 25 WVDC electrolytic capacitor IC1 IC2 555 timer oscillator integrated circuit 9 VOLT BATTERY 7 UU EXTERNAL POWER SOCKET d Fig 2 The Electronic Siren s printed circuit layout is shown with the components correct orientation properly soldered Clip off all excess wire and leads Then connect the battery to the Siren it should make the characteristic hee haw sound What To Do Next The circuit should be placed along with a small speaker on off switch and extension power socket in a project box The slotted enclosure shown allows the cir
196. is not usually appropri ate for low frequency work if the frequency of the input signal is below that of the oscilloscope s baseline generator that generator cuts in between cycles of the displayed wave form When the DC coupled automatic triggering mode is used 986 g834d NVTC A Fig 1 When DC coupled auto matic triggering is used it is important that the displayed waveform cross the 0 volt line Otherwise as shown untriggered operation will result Fig 3 Oscilloscopes display peak to peak voltages AC voltmeters provide rms measurements Fig 4 In the AC coupled mode there is no way to be sure that the baseline of the displayed waveform A is actually 0 volts In B the DC coupled mode has been Selected there the signal shown in A can be seen riding on a DC voltage of 3 Note the change in the VERTICAL ATTENUATOR Settings Fig 2 On a dual trace scope assuming that the two HANDS ON ELECTRONICS rh the trigger signal is generated when the signal passes through an imaginary line on the display representing O volts usually the center of the screen Note that it is important to be sure that the waveform does cross through that line or an untrig gered display will result See Fig 1 The positioning of the trace can be altered by using the VERTICAL position control to ensure that triggering does occur Whether triggering takes place on the leading or trailing edge of
197. itor project page 49 Spring 1985 experienced a problem He built three 3 units at the same time and all three appear to have the same problem it would appear that a difference in vendors of the LM3914 and a variation in lead lengths in the vehicles may be creating a situation whereby more than one LED will be lit at the same time even when in the Dot Mode of operation All the units work fine on the bench but they begin to act up when placed into the car D D Skokie IL The unit does have a tendency to break into parasitic oscillation and would under certain circumstances cause more than one LED to light at once The first red LED would be lit very dimly if viewed in darkness That prob lem has been traced to poor filtering on the input line Install a 5 10 zF tantalum capacitor across the pins where the volt age is supplied to the IC The same effect can be had by a 1 uF capacitor from pin 5 to the common V lead Both changes may be made but chances are Binary Bingo FUN WAY O Projects 4 1 of the first ten Proje because the components are not soldered they are a A great school project it s a fun game but even more it demonstrates binary num bers very well And they re the basis of all computers It seems pretty simple to play but try it Cat K 2600 ki siser and it s live because it uses YOU as the ncte generato You get an amazing range of control il
198. k may be placed in parallel with the batteries so that an external power supply may be used PARTS LIST FOR THE SIMPLE AUDIO AMPLIFIER C1 10 pF 16 WVDC electrolytic capacitor C2 10 LF 16 WVDC electrolytic capacitor C3 0 01 wF 16 WVDC ceramic disc capacitor C4 100 F 16 WVDC electrolytic capacitor C5 0 047 F 16 WVDC ceramic disc capacitor C6 470 F 16 WVDC electrolytic capacitor D1 1N914 small signal silicon switching diode Ri 10 000 ohm V4 watt 5 fixed resistor R2 68 000 ohm watt 5 fixed resistor R3 1000 ohm 4 watt 5 fixed resistor R4 2200 ohm watt 5 fixed resistor R5 22 ohm Y4 watt 5 fixed resistor RV1 10 000 ohm trimmer potentiometer TR1 TR2 TR3 TR4 DS548 or 2N2222 NPN silicon transistor T1 Audio coupling transformer 3000 ohm to 3000 ohms T2 Audio output transformer 1000 ohm to 8 ohm center trapped ADDITIONAL PARTS AND MATERIALS Printed circuit material 8 ohm loudspeaker 9 volt tran sistor battery battery snap enclosure solder hook up wire etc A complete kit of parts minus the 9 volt battery catalog No DSFW2 K 2630 for the Simple Amplifier circuit is available from Dick Smith Electronics P O Box 8021 Redwood CA 94063 priced at 6 50 Tel 1 800 332 5373 polarity and position before connecting the battery To test the Simple Amplifier connect the battery and short a wire across the input terminals That should produce a clicking so
199. l need a suitable printed cir cuit board of your own design and the parts Another option is to use perfboard or pre etched experimenters board However a complete kit is offered by the supplier given in the Parts List Check off the components against the list to make sure they are all there and are the correct types and values Assuming that you ve purchased the kit mount the components as shown in Fig 2 Place and solder the resistors and capacitors first taking extra care with C and C3 as they are elec trolytic and therefore polarized Make sure that all components are positioned neatly and properly dressed before solder ing them in place Next mount TRI in the correct place and with the correct polarity taking par ticular care because it will fit either way Notice that the emitter E collector C and base B are clearly marked on the transistor match them up with the correct pin holes in the board Solder the tran sistor in using a heatsink to prevent damage from overheating Now move on to the integrated circuits ICI and IC2 Those may be the first IC s you have ever attempted to solder in but if you follow the steps and you will find that It s not too difficult Insert the IC into the holes on the circuit board until the little shoulders on the pins prevent it from going farther making sure that it s cor rectly oriented with pin marked with a small circular indentation connected to the negative bus which
200. ld makes mention of 48 volts DC ori ginating at the telephone exchange In my area that voltage is 52 5 volts DC The voltage at my telephone is 51 7 Basic Amplifier Use to make the intercom proiect 18 or use as a gene purpose amplifier eally handy good sound output too Cat K 2630 6550 Intercom Build your own intercom amp use it around the home Practical simple to build with the intercom amplifier above Project 10 Cat K 2638 895 Shortwave Receiver You will be able to tune a variety of short wave sta tions or with simple modifr cations emergency seces l and amateurs etc Easy and tun tc Build 6 Cat K 2640 Pipe Locator Extremely handy for loca ting pipes wires etc in walls before dritling holes Sur prisingly effective for such a simple circu Cat K 2633 P 650 Mono Organ Snazzy little circuit uses the back of the PCB as the an keyboard Play a tune it s easy Cat K 2626 755 Touch Switch Ever wondered how those Hft buttons worked Builc this touch switch yourself and you ll be able to work i out Vanety of functions explained 650 Cat K 2628 Ding Dong Doorbell Yes it actually sounds like a great old fashioned door bell But it s electronic and you can build it 450 Cat K 2622 These kits do NOT include instructions AM intem iS published in Fun Way Vol 2 which is necessary before 1 construction can b
201. lephone isn t connected to the line There is probably an internal problem in the instru ment To check the ringing voltage you simply dial your local telephone company s ring back number and hang up the phone If you don t know that number ask a friend to call UNUSED SHORT YELLOW LEAD R 15K GREEN AAA UNUSED BLACK LED 1 MODULAR RED x TELEPHONE PLUG GRN MODULAR PLUG FRONT VIEW LONG LEAO NEXT TO FLAT EDGE BLK GRN RED YEL Fig 1 The Quicky Telephone Line Tester consists of only two components a 15 000 ohm resistor and tri color light emitting diode The tri color unit is actually two LED s red and green housed in a single package that are connected reversed bias and in parallel with each other Thus when one is turned on the other is off When an alternating current is applied the two LED s alternately glow giving the appearance of a third color yellow Tack solder the resistor to the short lead of the LED Slip the plastic tubing over the modular cord push it back out of the way and tack solder the LED s long lead and the resistor See Fig 1 Slide the plastic tubing up to the LED F it s loose apply a drop of glue where the tubinc meets the Telephone Line Tester just plug it into a modular jack he LED s glow and color tells ail is okay well maybe you At the instant the phone is hung up the tester will glow After a few seconds the tester will f
202. licker intermittently indicating that there is ringing voltage If the phone doesn t ring in step with the flickering or doesn t ring at all the problem is most likely a defective ringer circuit in the tele phone In that instance the easiest thing to do is simply borrow another phone and try again If the new phone rings the old phone is defective If the new phone also doesn t ring it s time to call the local telephone company their ringing voltage might be too low Why Worry About Polarity A logical question is Why worry about the polarity of the jack s wiring What does it matter if the glow is red or green Normally polarity doesn t make any difference at all to a conventional telephone or to accessories like an answer ing machine But some aftermarket equipment is sensitive to polarity For example some conference devices which simply connect two telephone lines together disable both lines if the polarity of one line is reversed In addition some telephones may ring or tick when an extension on the same line goes on hook is hung up if the polaritv at one jack is reversed Normally the telephone installer should have wired the jacks so that the green wire is positive and the red is negative cord s insulation To use the Quickie How It Works LEDI is a Tri Color light emitting diode which actually consists of separate green and red LED s in a single package and wired back to back as shown in Fi
203. ling the positive and negative indicators LEDI and LED2 Their inputs are crossed so that LED2 does not fire until the positive supply is at least 0 5 higher than the negative and the positive indicator does not go off until the negative supply is at least 0 5 higher than the positive in relative levels That overlap permits both LED s to be on when the two supplies are in 1 or better balance The 10 R7 RS R9 string drives the other two com parators which control the wARN indicator If either side of the supply is 10 or more higher than the other one of the two comparators will switch its output low and light the red LED3 the LM339N has opened collector outputs allowing such wired or connections The inputs are not crossed as with the other comparator pair so there is a band in the middle where neither comparator s output is low so the LED remains off Note that the schematic diagram Fig 1 shows 28 000 ohm resistors used for RI R3 While that value is standard in 1 units it is not in 5 resistors However by measuring the actual value of several 27 000 ohm 5 units you are sure to get exactly what you need Construction There is very little that is critical about the construction of the Power Supply Balance Indicator It can be built on per fboard using point to point wiring techniques soldered or wire wrap or you may choose to etch your own board it s your choice The pinouts for the integrated circuit and the
204. llow an oscilloscope to measure DC voltage levels Consider the waveform shown in Fig 4A Assuming that the vertical attenuator is set for 10 MV PER DIV and AC coupling is selected it shows a 40 mv peak to peak squarewave However there is no way to know whether the baseline is actually zero volts In Fig 4B the same signal is shown but there DC coupling is selected which reveals that the AC signal is superimposed or riding on a 3 volt DC voltage Note that the vertical attenuator has been reset to i vOLT PER DIV The O volt line had been previously established as the fourth middle line of the graticle using the GROUND position of the INPUT COUP LING switch Oscilloscopes are also used to measure the period di rectly and frequency indirectly of a waveform The period of the waveform is easily found by counting the number of divisions each cycle occupies and multiplying that by the setting of the time base For the triangular wave of Fig 5 assuming that a time base of 5 Ms PER Div has been selected the period is simply 20 milliseconds Since the frequency is simply equal to divided by the period here it is equal to 5 Fig 5 Oscilloscopes can be used to determine the period directly and the frequency indirectly of waveforms displayed on the screen of the CRT kHz When calculating the period or frequency of a wave form be sure to take into account the effect of a magnifier if used X Y measurements The X
205. m Selecting the triggering in that way ensures that there will be only one sweep for each output pulse Also some dual trace scopes have composite triggering In that type of triggering the trigger signal is derived from both channel and channel 2 as the display alternates be tween channel and channel 2 so does the trigger source The result is that both signals are solidly locked in despite any differences in phase or frequency Making Measurements Now that we have a locked in i e triggered waveform displayed on the CRT we need to interpret what it is we are seeing Consider the display shown in Fig 3 In it we see a sinewave To obtain the AC voltage of the waveform we need only count the number of divisions between the positive and negative peaks of the signal and multiply that by the vER TICAL ATTENUATOR setting For instance if the attenuator were set at VOLTS PER DIV the voltage of the signal shown in Fig 3 would be 8 volts But what kind of AC voltage are we measuring Readings obtained using an AC voltmeter are rms root mean square But oscilloscopes can not measure rms voltages cirectly the waveform observed on an oscilloscope is peak to peak For a sinewave the two quantities can be related to one another through the equation Vp 1 414Venus For a squarewave the peak to peak and rms values are identi cal For more complex waveforms more complex rela tionships exist We can use DC coupling to a
206. m which shorts out all the pins and prevents damage from static charges Leave it in the foam until you are actually ready to solder it in place Insert ICI into the holes on the printed circuit board Make sure it is the right way around by 0 D 0 u u 9 Fig 3 A single Dice printed circuit board fits easily into the Zippy box along with the battery If you want to add a jack so the circuit can be powered from an external supply wire the jack in place of or across in parallel with the battery connector Fig 4 Wire the double LED Dice as shown Note that in making the double unit there are a number of components that not needed on the second board noting that pin 1 marked with the small circular indentation on top is connected to the negative track on the circuit board Turn the circuit board over and carefully solder each of the pins to the pads mak ing sure that you don t run solder between the pads Solder one wire to the pushbutton switch then connect and solder the free ends to the circuit board at the position marked PBl You are now ready to con nect and solder the battery snap wires take care to see that you have the red positive lead going to the pad marked t and black negative to the pad marked After checking to make sure that all components are correctly in serted and soldered connect the battery then check the circuit by pressing PB1 All LED s should appear to come on di
207. m pus que um z e 2 e o 9 o Te eum H am Ou qm Ss es qum que quum qu ug a ap pss eum ap eu cum aum gum gum Gua ep ux hw ae Fig 4 Foil pattern for the solder side of the Before and After Clock s double sided printed circuit board If you etch your own board using this pattern and the one shown in Fig 5 be sure that the two line up properly PRINTED mg CIRCUIT DUE BOARD 7 ee ee S niaii m maT due Sis m eene ecu enean as aa Ee E ire L nS NU ION Ls E os TRU rn ned n k aT ite tty a ase 1 MXVI EXKL Oca Ll Sta a tl gt LE T ds From that point the count continues until 30 appears and then repeats One more thing happens at 30 The 10 s of hours counter which is only an up counter gets a pulse from U16 b pin 13 through inverter U17 c pin 15 At a count of ten the ten s of hours display lights and the hours readout then changes to the next hour For example if it was 29 AFTER 9 then 9 30 then 29 BEFORE 10 With the 10 s of hours counter at nine the next count a 0 is decoded by U9 b through U8 a U8 b U8 c U8 d 0 z 9 LTT eee AALL Deceesee An overhead view of the Clock s printed circuit board mounted in its housing At the top note that the power supply components including the resistor network R36 and R37 and excluding the power transformer T1 are mounted on a barrier terminal strip Pin of U9 b goes low causing the U8 e pin 12 to go high
208. mal number It means that one input pulse occurred When the second input pulse occurs the A flip flop is toggled again This time it switches from the 1 to O state As Fig 1 Four bit binary counter All J and K inputs to the flip flops are connected to a binary 1 high Flip flop toggles on the trailing edge of T count input to T 9861 834d NVf co an HANDS ON ELECTRONICS e eo NUMBER OF INPUT PULSES D ONO 91 00 WHO O00 O CO Cocda nd a a O0 Oo 00 00 7 O 0 000 0 O0 Fig 2 Truth table for a 4 bit binary counter its state changes the A output switches from high to low That in turn causes the B flip flop to toggle and set As the B flip flop sets its normal output goes from 0 to The transi tion appears at the clock input to the C flip flop but the flip flop ignores low to high transitions Looking at the counter outputs you see that the number stored there is 0010 or the binary equivalent of the decimal number 2 Two input pulses have occurred If you continue to apply input pulses to the counter one flip flop will simply toggle the next in sequence and the binary number stored in the counter will simply increase by one for each input pulse that occurs When that happens we say that the counter is being incremented The counter counts up from 0 to the maximum value that the counter is capable of holding Figure 2 shows the truth table of the 4 bit binary counter
209. ment display would show 00 if it were not blanked The minute s zero decode at signal U12 b pin 13 and the 10 s of minutes zero decode signal at pin 1 of U7 are respectively fed to pins 2 and 1 of U13 a That causes pin 3 of U13 ato go high causing QI to turn on and light the O CLOCK lamp Il The clock now reads O CLOCK At the same time D6 goes low inhibiting the BEFORE lamp for one count At the end of the hour decode U12 b pin 1 goes low causing U15 pin 4 to reset Pin 13 of U15 goes low causing U17 pin 2 to go high causing 14 to light so that AFTER is displayed on the front panel Also pin 10 of both U4 and US goes high causing them to start counting up Pin 4 of U17 b goes high and causes U18 b the one shot multivibrator to trigger the preset enable inputs of U4 and US Those counters had been preset to a 1 on U4 and a 0 on U5 Thus after Il the O CLOCK lamp has gone out the next display will be 1 AFTER Leading zero blanking is used on U2 to permit the readout to display Ol AFTER Whenever the Q outputs of US are all low U7 a pin is low which pulls the cathode of D4 to ground blanking the seven segment display HANDS ON ELECTRONICS T e j pell f 0 0 a A 2 lob p eum Q o o Com em em iala a z es a ea eum Lo d que Ze ea Gu e Q c l i 2 eum e oft Sm m em Q a e em Em Q Ge cm
210. mly one should come on brightly when you release the button then slowly die out Higure 3 shows the circuit and the slotted project box in which it will be housed The panel has holes drilled to accommodate the those components that are to be mounted there What To Do Next It is very easy to add a second die circuit for games such as Backgammon Monop oly etc where two dice are normally thrown at one time Of course you could simply build a second die circuit identi cal to the first and press both buttons at one time but that s inconvenient Our method of mounting the second die avoids the second pushbutton and indeed few other components by sharing some of the functions between the two Dice as shown in Fig 4 Obviously we cannot share the os cillator components or the counter as we would simply get a duplicate reading be tween the two dice So two individual oscillators and counters are provided giv ing two completely random numbers Because of the tolerance of compo nents the two oscillators will run at dif ferent speeds even though we use components of nominally the same val ue To build the dual dice you will need to build two kits The first is exactly as we have discussed you could use your single die if you wish The second is virtually identical except that D1 C2 and C3 as well as the wires to the switch and battery are left out Where shown in figure 5 jumper the two bo
211. mmand Dial Device Number 1 8 2 Turning a Device OFF Dial 0 then Device Number 1 8 3 Turning All Lights ON Dial 9 4 Turning All Devices OFF Dial 0 then Dial 9 Operation 1 Turning a Device ON The numbers through 8 on your telephone dial corre spond to the remote control module s unit device code If for example you want the telephone number 2 to control a specific switch module set the wall switch module unit code to 2 To eliminate possible interference with the telephone com pany s central office circuits the two operations should be performed within 15 seconds after the access code is entered Practice Session Let s turn all the lights on l Lift the telephone off hook and wait approximately one second Continued on page 102 Eres a as Lj A 1 e i The Telephone Remote Control Unit with the cover removed The AC line cable left and the input and output telephone cables right pass through holes in the plastic box wrap around screw mounting posts used to secure the cover and connect to the circuit board The posts provide cable strain relief 986 34 NV N 1 800 344 4539 AK Puerto Rico 218 681 6674 Telex 62827914 TWX 9103508982 DIGI KEY CORP am NATIONAL SEMICONDUCTOR PANASON L MM OC MACHINE EWC INC INTERSIL AD yy 256K 262 144 x 1 DRAM 150NS 5 70 1 39 95 9 te CW INDUSTRIES AMDEK O E E F JOHNSON ATLANTIC SEMICO
212. ms of convenience and cost effectiveness be cause 5 MB gets used up quickly by much of the new super sophisticated software Also a good part of the cost of a hard disk upgrade is represented by the disk con troller which is the same price of 5 10 20 30 and 40 MB units In fact it s often wise to consider going directly to a 20 MB unit because the additional 10 MB does not increase the overall costs dispropor tionately That is the price to perfor mance relationship isn t linear 20 MB doesn t cost twice as much as 10 MB usually the difference is less than 25 Three Kinds Of Hard Disks There are basically three kinds of hard disk upgrades Internal external and ex ternal expansion The kind that you can use depends on your particular computer The least expensive is an internal drive that replaces an existing drive or one that fits into a space reserved for a floppy disk drive Either way vou end up with one floppy and a hard disk An internal hard disk usually steals power from the computer s power supply so you must be certain the power supply can carry the extra load And if it can t you must use an external power supply for the hard disk unit External hard disks are used when there s no room inside of the computer for unit or you want a hard disk in addition to the computer s normal complement of floppies External hard disks can be nothing more than the hard drive itself installed in its own a cabinet
213. n in the voltage at the collector causes a similar voltage drop to be transmitted to ICI via C2 which immediately triggers the IC into conduction causing current to flow in the relay That in turn causes the relay contacts to close allowing whatever Alarm device that s connected to its con tacts to operate When the IC fires the short circuit across C3 and C4 is removed and they begin to charge through R3 After a delay of around 5 minutes the voltage across the capacitors rises above the threshold voltage of pins 6 and 7 and the IC is forced off Thus the relay drops out and the Alarm device stops The Alarm dura tion may be reduced by reducing the val ues of R3 C3 and C4 or increased by increasing them If a door or window has been left open the Alarm will not retrigger thus obeying noise laws However if the window door etc is closed and subsequently reopened the Alarm will be triggered Construction Details The first thing that we have to do is to get a printed circuit and all the parts A kit pee N G E SWITCHES 9 O o0 z os SWITCHES o o aL M nnum MB KEY SWITCH 9 12 VOLT POWER INPUT 9 12 VOLT BATTERY LARGE TYPE TANTALUM Fig 1 The complete schematic diagram for the Home and Car Alarm shows that the sensors can be wired in two ways the input that enters the circuit through the base of TR1 is
214. n the continental U S Alaska ena NET Hawan Canada arnt Mexico T 3 98 Less 10 z lege d BY PHONE CALL 1 800 344 4539 AK call 218 681 6674 BY MAIL SEND YOUR ORDER TO DIG KEY P O Box 877 Thief River Falis MM 58701 2 i i v pay money order Master Charge VISA or C O D DIGI KEY GUARANTEE Any parts ot products purchased from Digi Key that prove to be detective wit be replaced or retund vee 89 Dye bk es a gt a Less 25 ed if returned wrthun 90 days from receipt with a copy of your invoice PRICES SUBJECT TO CHANGE WITHOUT NOTICE CIRCLE 705 ON FREE INFORMATION CARD Telex 62827914 TWX 9103508982 DIGI KEY CORP C OR PORATION AK Puerto Rico 218 681 6674 Ok MACHINE SEWC ING v INTERSI e 17714 1290K 262 144 x 1 DRAM 150NS 5 70 1 39 95 9 JSTRIES Cw INDUSTRIES AMDEK GE EAC INC J W MILLER AAVID ENGII Factory Firsts UNGANT YAGEO J W MILLER LUXO OMHNSON ATI ANTI PND MIC AR e P D SUBMINIATURE ASSEMBLIES E EMIT Numeric Oisplays FEMALE MasterCard Fe LY CARD EOL 23634 21200 75976 72330 28504 7644 00 IWIT 590 24 878 83 5 35415 4 72 75 34009 304725 38008 346425 14005 393975 39892 35 7250 4i595 1899250 1552 162250 45520 497500 140G 460000 502 00 53875 SOCAL 8515 6 M A516 18ND R51 36 MO 851 B ND R51 18 w 851 36 SE 8515 amp ND R518 B i A518 36 ND R51B amp ND A519 18 Nfl A519 35 SD A
215. nce indication from the indicator LED s There fore that resistor pair should be matched as closely as possible The 1 units need not be purchased By measuring the actual resistance of several 100 000 ohm 5 units you can come very close to the specified value with the two resistors well within 1 of each other The other pair of 100 000 ohm units R7 and R9 are not as critical an un matched tolerance of 1 will be adequate but using the method those two units gives greater accuracy The circuit board of the Power Supply Balance Indicator can be mounted anywhere within the power supply where there is room All of the components except the three LED s should be mounted on the circuit board The positive and negative power inputs and the ground input should be con nected to the power supply at the supply s filter capacitors The two inputs to the divider strings should be connected internally to the positive and negative output terminals of the power supply The three LED s may be mounted anywhere that is conve nient on the power supply s faceplate If the controls for the positive and negative sides of the supply are on different sides of the face the LED s may be mounted on corresponding sides and wired to the Indicator board If the controls are not arranged in that manner follow the layout in Fig 3 L3 PARTS LIST FOR POWER SUPPLY BALANC INDICATOR Ci C2 I uF 16 WVDC tantalum capacitor LED1 LED2 Jumbo yellow or
216. ncluding 9 volt bat tery catalog No DSFW2 K 2625 priced at 4 95 is available from Dick Smith Electronics P O Box 8021 Redwood City CA 94063 9861 g34d NV o m HANDS ON ELECTRONICS a e Mount the components as shown in the parts placement diagram Fig 2 resistors and capacitors first being careful to mount C2 and C3 capacitors the right way because they are polarized If you are building the broach C1 is also an elec trolytic and requires the same caution as C2 and C3 in mounting It is possible that in some cases you will have an axial lead electrolytic to mount on the circuit board If there is space provided between the holes you can mount it flat as you would a resistor but if there is not the unit may be mounted in an upright position Take ex tra care that you get the polarity right Solder the six LED s in place making sure that they are properly oriented tre member that the short lead 1s the cathode K also marked by the flat side of the LED Keep all the LED leads at the same length to facilitate mounting in a suitable enclosure Place Dl in position and once you are sure that it s correctly oriented the banded end nearest TR1 s mounting pads solder it in place Install TR1 mov ing with caution and solder it in place Note that the base of TR1 connects to R2 The 4017 integrated circuit is a CMOS device and therefore static sensitive It is supplied stuck into special conducting foa
217. nd flip flops The flip flops are the primary components as they are used to store binary states Those states can be changed by input signals to form new states As a result the Outputs change in response Sequential logic circuits are designed to perform a variety of storage and timing operations A sequential logic circuit can retain a binary word or manipulate it in various ways Sequential circuits can also perform many different kinds of timing and sequencing operations The two most commonly used sequential logic circuits are counters and shift registers Virtually every digital circuit contains either a counter or a shift register of some type Binary Counters A binary counter is a sequential logic circuit made up of JK flip flops that together count the number of input pulses that appear at the input The counter stores the number of input pulses that occur as a binary number To determine the number of input pulses applied to the counter you simply look at the flip flop outputs and read the binary number stored PARALLEL COUNTER OUTPUT A LSB B C D MSB RESET OR CLEAR there Many digital circuits require that you keep track of the number of pulses that occur at a given point in the circuit A counter is used for that purpose Figure shows a logic diagram of a simple 4 bit binary counter The JK flip flops are designated A through D Note that the normal output of each flip flop is connected to the clock or toggle T
218. ndicate the sequence of events that occur during the two types of operation The upper diagram shows what happens when a single module is addressed The lower is the sequence that occurs when addressing multiple individual modules see text for clarification zero crossing which is a pre condition requirement prior to transmitting to the remote control modules The second sig nal Tl monitors the telephone line and provides ring dial information to the microprocessor for processing The telephone interface uses an opto isolator which con nects to terminal T on the microprocessor and is used to monitor and record dialing pulses and the ring signal without introducing any harm or disturbances to the telephone line With the phone line properly connected the forward dynamic impedance of the 4N33 LED light emitting diode is con siderably lower than the resistance value of R12 and R13 Lifting the phone from the cradle places approximately 300 ohms resistance across the line causing 20 milliamperes of line current to flow Since dial pulses are a quick succession of line current interruptions most of the current flows through the LED causing 5 volts to ground pulses at terminal T of the same duration With the phone in its cradle on hook the incoming ring signal is approximately 20 Hz 90 volts rms An inverse diode D1 is paralleled with the LED to provide for the AC currents during ringing The timing diagram of Fig 5 depict
219. ndicated by dashed lines are located under components DIS4 U2 U4 U6 U7 U9 and St After all the jumpers are in place mount the balance of the components As always exercise care when handling the CMOS chips to prevent electrostatic damage to the components Pins 3 and 6 of DISI and pins 9 and 14 of DIS2 were clipped off Those pins are not used and eliminating them simplifies the circuit board layout The power supply chosen will depend on whether a carry around portable or an AC powered device is desired The power supply chosen which should output 6 volts with a current of at least 150 milliamperes will dictate the final enclosure size Four C or D type cells can furnish adequate power for a portable model Or a small plug in wall power supply can be used to power the circuit from any 117 VAC outlet A third option would be using rechargeable batteries and a charging supply several of which have been presented in past issues of Hands on Electronics and Radio Elec tronics When your Digital Cribbage Board is complete and you sit down across the table from your opponent you will definitely find that keeping score is effortless faster and a lot more fun than the conventional Cribbage board and pegs You may still lose the game sorry to say we still haven t figured out how to make every one a winner But at least the circuit helps to cut down on the problem of scorekeeping W The author s prototype is housed in a sim
220. nergy encounters that gross mismatch and is promptly reflected up the line again to the antenna where the major proportion of it is radiated and a minor proportion reflected After a couple of such journeys virtually all of the energy will have been radiated In typical audio 8 02 03 05 08 2 3 4 586 8 1 LINE LOSS WHEN MATCHEO dB Fig 2 The graph indicates the amount of additional loss due o SWR which occurs for various values of cable loss when the cable is correctly terminated to a resistive matching load 9861 8343 NVfP P Ce HANDS ON ELECTRONICS D amp transmission systems the time delays involved are not impor tant Ina TV transmission system they can be significant and more careful designing is necessary to avoid transmitting ghosts Cable Losses In fact there is a flaw in the previous argument We can only assume that no energy is wasted if we ignore the inherent losses in the cable All cables have some losses and those increase with frequency For example a popular foam filled coax RG 8 U has a loss of 0 9 dB 30 meters at 30 MHz which rises to 3 5 dB 30 meters at 400 MHz The presence of such losses means that any signal which has to traverse the line more than once will suffer additional losses on each excursion So we have to concede that in practice standing waves do create some loss But how much and how important is it If we assume a 3 dB loss in a cable system which is correctly te
221. ng Simply complete the form on this page of the Market Center and we will bill you E SATELLITE TV SATELLITE Handbook and Buyers Guide tells ev erything you need to know 10 00 SVS Box 422 Seaford NY 11783 BUILD your own Satellite TV receiving system and save Instruction manuals schematics circuit boards parts kits Send stamped envelope for com plete product listing XANDI 201 E Southern Suite 100 Dept 32A Tempe AZ 85282 BUSINESS OPPORTUNTIES US 8 00 including disk thousand name brand pro grams for Penis IBM PC details US 1 00 RELIANT P O Box 33610 Sheungwan Hong Kong DO IT YOURSELF TV REPAIR NEW Repair any TV easy Anyone can do it Write RESEARCH Rt 3 Box 601BR Colville WA 99114 BUY BONDS 9864 g34 NVP vado o N HANDS ON ELECTRONICS e eo JAMIT Even the Very Best Radar D Detector es Protect alL from the Nev Wes Rad Radar uana Caunpact vunser cashi uir causes radar guns ia pel wt a percentage ni yeur true ap d whyitwer speed voc dis c Cr new TEAD S mde w prevent rman from obtaining amy reading i ter Escott or ather detector Bes defense again itestatil radar Oo raies oo bili X amd K band WARNINGE Ti ME UNE ase against mede radar andis tint FOC ponit Transmitters Tre hearbor che Jammer is the Le oh plor iter In the past these were n ani li Li caly about LOO allies iM We uem frase eui orn Lda Cou High Power Transmit
222. ng coodinator 714 760 8697 Hands on Electronics ISSN 0743 2968 Published by monthly Jan Feb March April May June July Aug Sept Oct Nov Dec by Gernsback Publications Inc 200 Park Avenue South New York NY 10003 Second Class postage pending at New York NY and at additional mailing offices One year s x issues subscription rate U S A and possessions 14 00 Canada 17 00 all other countries 21 00 Subscription orders payable in U S funds only E postal money order or check drawn on a U S A bank U S single copy price 2 50 1985 by Gernsback Publications Inc Ali rights reserved rinted in U S A Postmaster Please send address changes to Hands On Electronics Subscription Dept P O Box 338 Mount Morris It 61054 A stamped self addressed envelope must accompany all submitted manuscripts and or artwork or photographs if their return is desired should they be rejected We disclaim any responsibility for the loss or damage of manuscripts and or artwork or photographs while in our possession or otherwise As a service to readers Hands on Electronics publishes available plans or information relating to newsworthy products techniques and scientific and technological developments Because of possible variances in the quality and condition of materials and workmanship used by readers Hands on Electronics disclaims any responsibility for the safe and proper functioning of reader built projects based upon or from plans
223. nt _ reprints 7 00 each plus 1 for han Street aadress 1 dling amp First Class postage Ihave enclosed N Y State residents must add Sales tax U S and Canada only s c m control modular and switches throughout the house lat Jensen on DX ing Continued from page 22 nels below 6 MHz megaHertz With re ception generally limited to the hours of darkness the higher static levels co channel interference from other stations and in short tougher reception condi tions SWL s often tend to avoid those bands Finally while some of the major sta tions in South America have English lan guage programming most broadcasts are in Spanish or Portuguese Still if you re bold enough to try you ll find much listening enjoyment particularly in the musical offerings and some exotic catches among those sta tions To get started if you ve been avoiding Latin America DX ing thus far here are some stations to dial Some have English broadcasts some don t Almost as sure as death and taxes is the likelihood that one of your first South American loggings will be HCJB the Voice of the Andes in Quito Ecuador HCJB is a religious station which has been on shortwave since the 1930 s t was my very first SW logging back in 1947 so it retains a special place in my memories Signals are strong and there are plenty of English broadcasts You can find HCJB on several freq
224. ol Sys tems Inc P O Box 78 South Windsor CT 06074 Kit 1 Kit of all parts including programmed EPROM and miscellaneous items 92 50 Add 4 00 for ship ping and handling Kit 2 Programmed EPROM and etched drilled plated through printed circuit board 26 00 Add 2 00 for shipping and handling Connecticut residents include 7 42 sales tax Please allow 6 8 weeks for delivery The printed circuit board for the Telephone Remote Control System is sized to fit inside a standard TEL hobbyist plastic box Corners are INPUT cut off so that board will clear AND the box s cover mounting posts OUTPUT Compare Fig 7 to this photo and observe that one resistor mounted caty corner replaces R11 and R15 The latter are connected in series The author found an unusual resist or not standard that filled the bill and used one resistor in place of two Hobbyists would not be that lucky so two resist ors whose ohmic resistance add to the desired value are used module or lamp modules turn on If not follow the previous installation instructions and reverse the red and green wires Using the Control System The Telephone Remote Control System operates when the telephone is taken off hook and the access code is entered followed by the device number to be turned ON or OFF The Control System allows you to perform two operations or events after the access code is dialed Those operations in clude Telephone Co
225. om the printed circuit board and in their place solder a 100 ohm resistor The two wires to the socket are then re soldered to the circuit board each one pad to the right of their previous position They now connect to the collector of TR1 and the negative supply The two sockets can be connected to gether via a short twin jumper lead Fig 3 The Amplifier circuit can be placed in a small slotted box and wired as shown with the speaker volume control and input jack mounted to the lid of the box 9V BATTERY NEW 10022 TUNING CAPACITOR RESISTOR i ae ICON Eu uu e ON OFF SWITCH TO SPEAKER l i 42 A5 TRA i RTO P uh E n3 C TAI B bs aw gt E 1 c C 1 Jn T TO VOLUME CONTROL Fig 4 By connecting the input of the Amplifier to a signal source in can be used in many applications for instance as an audio amplifier in a radio or intercom system with 3 5 mm plugs on each end A further refinement is to place both the radio and Amplifier s printed circuit in the same box running from the same battery and wired directly together to so that no sockets are involved as shown When wiring the portable radio and amplifier together note that the I00 ohm resistor is the only modification to the circuit It may appear that a battery lead has been left off the Amplifier board however the black ground lead is jumpered from the radio
226. omputer training plus career training in Robotics Data Communications TV Video Servicing and many other fields If some other ambitious person beat you to the card write to NRI at the address below McGraw Hill Continuing Education Center 3939 Wisconsin Avenue NW Washington DC 20016 3 We ll Give You Tomorrow IBM is a Registered Trademark of International Business Machines Corporation Y PARIS p nut nut gisca FAS D PS T LIGHTED ROCKER SWITCH 115 vac lighted rocker snap mounts in ULTRA MINIATURE 9 VDC RELAY g FuptsSu FBR211NEDO005M20 High sensitivity a x1Vs hole COL 120 onms E pal Orange lens 16 amp gt CONTACTS tamp contact Mounts in 14 pin DIP socket 1 50 MINIATURE TOGGLE SWITCHES ALL ARE RATED 5 AMPS 125 VAC S PD T S PD T S PD T on on on on on off on PC style Solder lug Sotder lug non threaded terminals terminals bumag r RUM cache u 1 00 each eac or 9 1 10 tor 7 00 7t 100 for 80 00 ted RR f 13 8 VDC REGULATED POWER SUPPLY A pity These are solid state fully regulated 13 8 vde DAT power supplies Both feature 100 solid state F A construction fuse protection and L E D power i A indicator U L listed IPS e 2ampconstant 4 amp surge 18 00 each d a Eh r ENSE Sampconstant 5 amp surge B PA SPEAKER C TS Model 8B3079 5 00 each bj He 8 ohms coil iba 3 002 ferrite magnet CASE OF ERN Typical response range 8 SPEAKERS vx 100 10
227. ons that reinforce your skills Learn to service today s computers As you complete your Sanyo you grasp the secrets that qualify you for a new career You ll learn to program in BASIC and machine language You ll use utility programs to check out the operation of the Sanyo s 8088 micro processor the same chip used in the IBM PC And you also get over 1 000 worth of software including WordStar and CalcStar Most importantly you ll under stand the principles common to all computers Only a person who fully understands all the fundamentals can hope to be able to tackle all computers NRI makes sure that you ll gain the knowledge and skills to maintain troubleshoot and service computers Learn at home in spare time With NRI training you ll learn at home on your own time That means your preparation for a new career or part time job doesn t have to interfere with your current job You ll learn at your own pace in the comfort and convenience of your own home No classroom pressures no rigid night school schedules You re always backed up by the NRI staff and your instructor who will answer questions give you guidance and be available for special help if vou need it Let others worry about computers taking their jobs With NRI training you ll soon have computers making good paying jobs for you Send for Free NRI Catalog Send the post paid reply card today for NRI s 100 page catalog with all the facts about c
228. ons we must have a way to preset the counter It is done with preset circuitry that takes advantage of the asynchronous set S and clear C inputs of the JK flip flops A typical circuit for one flip flop is shown in Fig 4 If you would like to preset the flip flop to binary 1 you apply a binary input to the preset input at gate A Then you apply a binary to the LOAD input That forces the output of gate A low and the output of gate B high The result is that the asynchronous set input of the flip flop causes it to store a binary 1 Applying a binary O to the preset input and then switching LOAD from low to high will cause the flip flop to be reset or store a binary Q When all flip flops in the counter have the preset circuitry shown then a parallel binary number can be applied to the counter and loaded into it prior to beginning the count opera tion To show how that presetting works assume that the 4 bit binary counter described previously has preset circuitry Sup pose we apply the binary number 1010 to the preset inputs and load it into the counter The counter outputs D C B A will read 1010 decimal 10 Then assume that input pulses occur If four input pulses occur the counter is incremented to 1110 The four input pulses increment the counter from 10 to 14 Down Counters The binary counter described previously is an up counter as each input pulse increments the binary number stored in the flip flop That is as each input
229. or DMM TPI has eliminated the nuisance of test leads accidentally disconnecting from the meter A thumb screw expands the banana plug inside the meter jack for a ught secure connection The LTL1000 is ideal for low voltage and resistance measure at both ends CIRCLE 736 ON FREE INFORMATION CARD ments Its silver plated contacts minimize thermal EMF and contact resistance The LTL1000 also features rubber shielded ba nana plugs for maximum salety and soft and flexible cables that have strain reliefs Ratings are 1000 volts rms 2 1 features a tri color indicator that lights up lt aes M7 7s P Economy Soldering Iron VAL MEL a ge General purpose main powered iron that s idea for all those hobbyist and technician jobs Comfy tapered handle and nicely balanced iron for hours of fatique free use Stainless steel barrel and 110 volt 30 watt element is just right for most assembly or repair soldering Great beginner s iron too Comes ready to use with hints on soldering Cat T 1300 Transistor Nipper 12 ha Ideal for PCB work Very sharp precision Di Qo cut with long life cutting edge 3 7 body with spring return 35 cutting blades Cat t 3205 Mini Needle pa et E e OS H id cou T a OR qois oO p Precise non serrated tip and jaw Ideal for use with semr conductors the very fine O4 tip
230. or information published in this magazine p sP 1 ee ee Build C ircuits Faster and Easier With Our 20 Solderless Breadboard Introducing the plug in world of AP Product s versatile low cost breadboaras Now you can design build and test prototype circuits just like the profes sionals and make changes in seconds No messy soldering or desoldering No more twisted leads or damaged devices With our ACE 109 and 118 blue bread boards you simply plug in components and interconnect them with ordinary hook up wire All sizes of DIPs and other discrete components up to 22 gauge lead diameters snap right into the 0 1 x 0 1 matrix of the solderless tie points anywhere on the layout You dont need expensive sockets or spe cial tools Buses of spring clip terminals form a distribution network for power ground and clock lines AP Products 100 series breadboards give you all the functions and flexibility of more expensive circuit evaluators The spring terminals have mechanic ally independent contact fingers to accommodate most DIPs and discrete components The ACE 109 has two terminals for separate voltages plus a ground con nection The larger ACE 118 offers the same three terminals plus an addi tional terminal which can be used for clocking or another voltage The back plates are heavy steel to keep the boards stationary Don t wait These low prices won t last forever See your local
231. or openers and aircraft and boat weather radar systems For more information on the RD 9 and RD 35 write to Uniden Corp of Amer ica 6345 Castleway Court Indianapolis IN 46250 Audio Video Cable Hitachi recently introduced the latest in its line of audio video cable which is said to offer superior reproductive quality The cable uses linear crystal oxy gen free cop per LC OFC a recent audio video tech CIRCLE 744 ON FREE INFORMATION CARQ LE muacm Cave Lid linear crystal cable provides dramatically lower distortion and reduced signals loss compared to conventional cable One crit ic claims that using the cable is equivalent to upgrading a full level in loudspeaker quality Hitachi researchers suspected that a major source of distortion and signal loss lay in the boundaries between crystals which act as a gap that electrical impulses have to cross One way to minimize the problem they reasoned was simply to reduce the number of crystals To do so Continued on page 18 With NRI training at home you can Move up to a high paying career servicing computers B Ww And you can sta mek E by actually buil wA s DEED wee eet E 4 ou ll puer L unam Rl L UNE I EP ds Loc nz Greg LM I MI 2 yp i f I see Eu Samer Wy sy oy LEE mon e MICH S2iNOM 12313 ding NRI s 16 bit IBM compatible computer You can create you
232. orbed all the energy with no bounce or reflection The same applies to our burst of RF energy When it reaches the end of the cable it will need to meet exactly the right load if all its energy is to be dissipated in that load And it doesn t take much imagination to conclude that the load should look like in that case a 50 ohm resistor that exhibits no reactance whatsoever If it encounters any other value then only part of the energy will be absorbed by the load and the remainder will be reflected down the line in the direction of the transmitter And that is what creates what are called standing waves on the transmission line Standing Waves In greater detail the standing waves are actually peaks of voltage between the conductors or peaks of current through the conductors which occur at regular intervals along the line They occur at those points where say the voltage of the outgoing energy encounters voltage of reflected energy which is exactly in phase with it Similarly for the current peaks The position of each peak is fixed and will always be one half wavelength away from its neighbor Exactly between each peak one quarter wavelength away will be a dip or voltage minimum and it is the ratio between those two voltages which constitutes our standing wave ratio or SWR Note wavelengths in coaxial cable will be physically shorter than in free space according to the characteristics of the insulating material A factor of
233. ore pulses are output by the timer The counter then shows the number to which it has counted during the time the PBI was depressed Because it is not desirable for the LED D1 1N4001 1 A 50 PIV rectifier diode LED1 LED6 Miniature red LED THROW SWITCH LED LED2 LED LED LEO LED6 3 4 5 to stay on indefinitely wasting the bat tery a separate circuit causes the LED to go out after a short time That circuit con sists of DI C2 TRI and its associated resistors Whenever PBI is pressed C2 charges via D1 That allows TRI to turn on When the button is released the charge on C2 is bled off through R2 and the base emitter junction of TRI After a short time the current through the tran sistor becomes too small to keep it con ducting so it turns off and the LED is extinguished With the 022 uF capacitor shown the LED s flash in sequence so quickly that they all appear to be on at once although dimly That s necessary so that anyone using the die will not be able to cheat by PARTS LIST FOR THE ELECTRONIC DICE C3 4 7 y F 16 WVDC electrolytic capacitor Fig t The circuit is very simple but take care with the CMOS IC and the LED s Note especially that LED2 LED4 and LED6 are oriented differently from LED1 LED3 and LED5 LT 9 VOLT BATTERY ON OFF SWITCH for the Electronic Dice is shown with all off board connections made If you follow this no trouble in getting th
234. oset for example We assembled the prototype into a project box with two terminal strips on the lid to allow for easy connection of the sensor wires terminal strips can be mounted on The circuit is easily mounted in a project EUNT the outside of the enclosure to allow box as shown in Fig 4 which further for easy connection to the sensors Fig 4 The Alarm circuit can be placed in a suitable box along with its two battery power supply Then PARTS LIST FOR THE HOME AND AUTO ALARM Ci 0 01 uF 16 WVDC polyester capacitor R5 47 000 ohms watt 5 fixed resistor C2 0 01 uF 16 WVDC polyester capacitor TR1 DS548 or 2N2222 NPN silicon transistor C3 C4 22 pF 16 WVDC tantalum capacitor ADDITIONAL PARTS AND MATERIALS C5 0 01 F 16 WVDC polyester capacitor Ena circuit material 8 95 Eo mo 9i m D1 D2 1N4002 1 A 100 PIV rectifier diode Mc MM cM NE m E du ede eps kaline batteries or some other 9 12 volt DC source 1C1 555 timer oscillator integrated circuit solder hook up wire etc R1 220 000 ohm watt 5 fixed resistor 4 R2 100 000 ohm 4 watt 5 fixed resistor A complete kit catalog No DSFW2 K 2635 of parts is R3 4 7 Megohm watt 5 fixed resistor available priced at 6 50 from Dick Smith Electronics R4 100 000 ohm watt 5 fixed resistor P O Box 8021 Redwood City CA 94063 HANDS ON ELECTRONICS o A MANUAL LIGHT _ __ TO POINT SHOWN TO SWITCH ON CIRCUIT DODR SWITCH
235. ositive wave Thus the frequency of the signal at the output of the bridge rectifier is 120 Hz and would require more division than is used in the Before and After Clock circuit Construction Building the Before and After Clock is rather straightfor ward whether you purchase the printed circuit board from the supplier given in the Parts List or etch your own board If you d prefer to etch your own board Fig 4 and Fig 5 show the foil pattern for the Before and After Clock s double sided printed circuit board But since the board is double sided you may want to go the easy route After you ve obtained the board the rest is simple For the most part all you have to do is stuff the printed circuit board with integrated circuits and a few assorted other compo nents as Fig 6 shows Just be careful that the integrated circuits diodes transistors and so on are properly oriented Integrated circuits of the B series are recom 2nded Once the board has been populated and all mponents checked for correct orientation bring out wires shown in the figure for the 12 volt power supply as it is not included in the printed circuit board layout the seven segment dis plays and time set switches S1 S3 In the author s prototype see top view of the unit the power supply was built on a barrier terminal strip using point to point wiring In building that portion of the unit refer to Fig 3 as a guide on how it should be wired
236. ou can connect them via short lengths of wire If you wish you can even try putting in a fixed value capacitor equal in value to the variable types and up to a few hundred picofarads and connect a small trimmer capacitor in parallel to give you very fine tuning E rr M R4 amp R6 SEE TEXT A LI i p M ey IN 500K um A EN yp POTENTIOMETER p E z ii JB rd ox EL Tm s 3 Qr os m T UAM Fig 2 The printed circuit board for the Shortwave Receiver is shown with the components installed by following that layout you should have no problem putting the circuit together zm scorrono rw Ya EU pone FE DOCTR e e e SIREN This simple electronic siren can be incorporated into your home brew circuits as a warning or signaling device LJELECTRONIC SIRENS HAVE MANY PRAC tical applications As a warning device or other type of signal it s hard to beat a siren This simple circuit simulates the hee haw sound that modern police si rens make But you re not stuck with that racket because it can be tailored to pro duce other sounds as well Further you can add a horn speaker to this project to make a first rate burglar alarm siren How It Works The Siren is a good example of how electronic circuits can control one an other In the Siren circuit see Fig 1 there are two oscillators one of which switches the other to pro
237. our TV set is a very expensive appliance It is also portable and marketable which makes it a prime target for thieves The simple alarm described here will sound off immediately the VCR is lifted and it makes a lot of noise The circuit could also form the basis of a burglar alarm for an entire house Cat K 3423 MY Home Alarm What a superb kit This highly developed design offers features which you d normally find only on units costing 9 Security key operation for both alarm function and box 2 instant and six delay sectors capable of handling Siren up to two speakers PLUS Bele dat and 986 34 NVC N HANDS ON ELECTRONICS co Famous U S Brand Dot Matrix PRINTER Factory reconditioned Factory warranty Compatible di with C64 Be SX64 VIC20 Educator 64 Plus 4 and C16 Here s a great opportunity to add a fine quality printer to your Personal Computer at a BIG SAVINGS Now you can get neat clean printouts of reports correspondence mailing lists charts inventories financial figures or anything else you have in computer memory And it all comes out at the speed of 60 characters per second These are factory reconditioned units that look and work as good as brand new And they re backed by the manufacturer s standard new product warranty Sorry we re NOT permitted to print the famous brand name in this ad But we can tell all if you phone
238. our house code on the Control System perform the follow ing procedure 1 Disconnect the plug of the Control System s AC TABLE 2 SWITCH SETTINGS FOR ACCESS CODES power cord from the 117 volt AC outlet 2 Select your new house code Remember to set al remote control modules to the same house code 3 Insert the plug of the Control System s AC power coard into a 117 volt AC outlet Circuit Description The Telephone Remote Control System can be divided into four sections Those include the power supply processor telephone interface and the RF oscillator The schematic diagram of the power supply and RF oscillator is shown iff Hg 1 The power supply is configured as a full wave rectifier consisting of a center tap transformer T1 diodes D4 and D5 capacitors Cl and C2 and voltage regulator U5 The voltage regulator is in its simplest form and provides 5 volts DC to all the integrated circuits Even though the maximum average power dissipated is below that required for no heat sink operation of the voltage regulator a heat sink has been designed onto the printed circuit board to provide a thermal safety margin The RF oscillator is basically an astable or free running multivibrator designed to operate at 120 kHz The two Sprague high voltage high current Darlington NPN tran sistor array drivers shown diagrammatically as inverter driv ers U4 a through U4 d are R C coupled the output of the second stage is couple
239. over the sound V Cat K 2669 49 5 FUN WAY THREE BOW is kit with two oft And what value Buy me ple Ue throw In the m nel i t pro dnbie eh e Electronic Cricke Sons alls Stridulus Grillidae plu Cat K 2610 its work too Cat K 2662 ON Mini Color Organ Your very owr disco colour organ but ours is battery operated so it s much safer than mains devices Connect it to your radio cassette or stereofor areal lightshow Cat K 2664 4995 friends as Noctu ether v8 Amplifier project E itself at no ex Fun Way Three Co K 2670 POR ONLY 2 95 in Fun Way One And UN WAY ONE VALUE PACK Di 0 Enables you to build any Ir reusable so you can build any other of the tirst ten projects too build these projects most popular ne one book FREE ject known t at 24 90 a Use tra charge good that only one of them will be re quired most likely the latter one The published diagram shows the Mode pin 9 connected to either pin 11 for a dot display or to pin 3 for a graph display Try pin 9 floating for the dot dis play and jumpered to pin 3 for the graph mode Pin 11 connection is used only when cascading more than one LM3914 for 20 or more dots Another problem is that the LEDS po larities are shown reversed in Fig 5 di agram The pictorial wiring in Fig 4 shows them wired correctly Check for RFI generation by tuning the car radio to a quiet spot on th
240. ow 0 the circuit is a down counter Instead of having a single count input like the up down counter discussed previously that counter has two count inputs To decrement the counter you apply input pulses to the down count input To increment the counter you apply pulses to the up count input The carry and borrow outputs have not been discussed previously Those lines are used when the counters are to be cascaded The carry output is produced by an AND gate that looks at the normal flip flop outputs It says in effect that the counter contents is 1111 That means that the counter is at its maximum value and the next input pulse will cause it to recycle to zero When it happens the carry output generates a pulse that is applied to the next counter in series so that the overflow will be recorded The borrow output is used for cascading the counters in a down count application The borrow output signal is gener ated by an AND gate that monitors the complement outputs of the flip flops When the counter 1s decremented to 0000 the borrow output signal is generated indicating that the counter is about to recycle The borrow output pulse is applied to the down count input to the next counter in series With those signals multiple counters can be cascaded to form binary counters with lengths of 8 12 16 20 and other multiples of 4 bits Binary counters have a maximum count capability that is some power of two Each time an additional flip
241. ows for greater power supply flex ibility Both the battery snap and socket for external power are included with the switch controlling the power supplied So far we ve shown a basic single LED flasher But as has been mentioned the printed circuit board was designed to op erate with either one or two LED s If you wish to add a second LED simply con nect it in place of the link with the anode the longer lead going to the track con nected to the positive supply Why not use a green LED in the second position so the indicator would alternately flash red and green If you do connect a second LED the 560 ohm resistor should be reduced to the same value as in series with LEDI for roughly equal brightness We ve shown a 330 ohm resistor in series which is fine for 9 or 12 volt operation If you want to operate the circuit from a lower supply voltage you might want to use a lower value resistor to get sufficient LED bright ness Values as low as 100 ohms should be satisfactory remember however that the lower the resistor the heavier the current drain on the battery Other modifications you can make to your flasher include the altering of the LED s on off times With the capacitors values shown the on time is much shorter than the off time If those capacitors are made equal the on off times of the LED s will be equal Watch the capacitor polar ity If you want to use the Flasher as an alarm device we assume t
242. per load The truth is that if the load is correct then that value will be seen at the other end of the cable regardless of its length If the load is incorrect then that value will be seen at half wavelength intervals along the cable But since it is wrong anyway there seems little point in trying to reproduce it In fact in such circumstances the length of the line can be critical for a quite different reason Between the half wave length points the cable will exhibit a range of impedances one of which may match the transmitter So by adjusting its length the cable may be made to act as a matching trans former and load the transmitter correctly But don t try to do it using the SWR meter because altering the line length will have no effect on the SWR If that trick is to be used other measurements must be used such as that from a field strength meter at a fixed distance from the antenna Stay away from trick solutions So after all that what is the role of the SWR meter Well it obviously isn t the universal answer to all antenna trans mission line problems On the other hand if it is the only instrument available it can be quite useful n important point to realize is that while it can indicate that there is something wrong with a particular set up it cannot indicate what is wrong Thus an antenna may present the wrong load for a number of reasons It may not be resonant the design may be wrong or may have been misinte
243. perly made Check all components to ensure correct position and polarity be fore connecting the battery Connect the battery and tune the radio by varying CVI until you pick up a station What To Do Next Because the slightest bump to the coil will cause the receiver to drift from the tuned station the circuit should be mounted in some form of protective case The circuit has been designed to allow no holes mounting in a slotted project box The power switch and volume contro po tentiometer are mounted on the front pan el of the box You can also fit a socket on the front panel for an external wall mounted DC power supply When the circuit board is placed in the slotted box the shaft of the tuning capaci PARTS LIST FOR THE INTEGRATED SHORTWAVE RECEIVER HANDS ON ELECTRONICS o o C1 0 001 uF ceramic disc capacitor C2 10 pF ceramic disc capacitor C3 90 0047 yF polyester capacitor C4 10 uF 10 WVDC electrolytic capacitor C5 0 0047 uF polyester capacitor C6 C8 0 0022 u F polyester capacitor C7 C9 220 pF ceramic disc capacitor C10 10 4 F 10 WVDC electrolytic capacitor C11 470 4F 16 WVDC electrolytic capacitor CV1 960 160 pF tuning capacitor D1 0A91 1N34 1N60 1N270 or almost any signal diode C1 4007 CMOS dual complementary pair inverter integrated circuit Li see text R1 47 000 ohm 4 watt 5 fixed resistor R2 1000 ohm V4 watt 5 fixed resistor R3 1 Megohm w
244. ple wooden enclosure without an internal power supply Instead the author opted to use a wall mounted power supply like those used for TV games and calculators GETTING INTO CRIBBAGE The game of Cribbage which dates back to about the 17th century has several variations five card six card and seven card However we will only concern ourselves with the most basic form five card Ta le 1 gives the the scoring combinations and terms used in the game Crib bage is usually played to 61 points or pegs but may also be played 121 the first player to reach that figure wins If when cne player reaches that score the other has not yet scored 3i or more 91 when the winning score is 121 he is said to be in the urch or simply lurched A more colorful word used is skunked Play starts by determining which player gets first deal by a cmt of the cards low card deals first Ace being the lowest Either player may shuffle but the dealer must shuffle last Five cards one at a time are dealt to each player face down the first going to the non dealer The non dealer immediately pegs advances his peg on the scoreboard unique to Cribbage three for last but only on the first deal of a new game If he fails to do so before the play begins he loses those pegs Each player then discards two cards face down forming a crib of four The crib belongs to the dealer at the end of that deal and any scoring combinations that are found in the
245. pment place a 120 5hm resistor in series with the current meter A dead short in the IC Continued on page 36 By Kenneth H Recorr ch POSITIVE ff ft ttt E vies LN LLL LL LLL LLLI MEL sees PN EN i l tetween terminal pairs of tae unknown IC up to 16 pins in size Copy it q on a Xerox machine so CCC a EE of signature charts aa In fact should your Xerox copier provide VOLTS TO GND mA TD Vec RES mA TO GND ii enlargements go for HAH Seger make your note taking easier 986l g34d NVTC i w THE MARK Ill HV CIRCUIT SCANNER Checks the horiz output circuit for open shorts Checks the flybeck yoke PC and HV mult Checks all scan derived B sources Checks all circuits that rely on scan derived B voltage Checks for open safety capacitor Checks the emitter circuit of the horiz Output THEN x Provided the green normal light is lit the Mark Iil will safely power up the TV set so that you can look for open circuits by examining the picture on the CRT Circumvents all start up and horiz drive related shut down circuits APPLICATIONS The Mark Il will analyze the horiz flyback hi voltage scan derived B sources yoke pin cushion HV multiplier cir cuits in any TV set that employs either an NPN transistor or a single SCR for its horiz output device This applies to any age any model any chassis any brand
246. practice most people tend to make it at the transmitter end When an antenna tuning unit or other matching device is used at the transmitter fitting the meter between the two is a perfectly legitimate way of determining when the tuning unit is presenting the correct load to the transmitter The main objection to measurements made at the transmit ter end is that the cable losses will mask the true ratio the forward signal having been attenuated before it was reflected and the reflected signal attenuated again on the way back Depending on the severity of the losses the user may obtain reading below what he has set as an acceptable maximum when in fact the true value is appreciably higher Unfortunately cable losses become worse as the frequency increases and in the 420 450 MHz 70 cm band that prob lem could be very real So be prepared to work at the antenna unless the coax line can be kept short In cases like that it is sometimes better to move the transmitter close to the antenna and use a much shorter line Summing Up The most important characteristic of an antenna system is to present the transmitter with its optimum load An SWR measurement can indicate whether that is happening and if not the degree of error It is valuable primarily for that reason the standing waves being relatively unimportant So let s keep things in perspective BEFORE AND AFTER GL CK A clock that talks your language it displ
247. quency operanon 12 ct 24 Hour Disoiay i fert Part No is length e Card Edge Connector iStyle X Few CG N SINN MN Sass a mo Pca 25 50 34 44 40 76 50 26 Number After Desh te Cable Langr amp in Fuer eca Coa OIG KEY Pricing tact Style Part No 1 io 10 R300 NO 115 10 18 l4 R301 Wf 129 Ita iB R302 SP 145 1278 20 A303 b 155 1325 76 R304 NO 18 1615 34 8305 NO 2 24 19 88 HU 306 D 268 2346 50 R307 ND 301 2346 10 R400 NO 10 35 20 H8401 ND 1226 26 R t02 ND 18 54 M RB403 NO 215 1905 0 RBAOA ND 244 2181 50 R 405 ND 308 2714 2 R500 ND 242 2148 26 ASOUND 286 2530 3 RSO ND 351 3105 a R503 ND 433 3657 23900 R504 NO AJQ 4163 27200 N co RJUS 36 ND 209 1847 R310 3640 238 2104 831136 D 2588 2372 8312 35 NU 28 2515 8313 35 ND 353 312 R314 35 ND 448 3980 8315 36 WD 21 4864 30382 263500 331 36 ND 625 5585 38880 302500 DNENE 10 86106 35 ND 1530 17475 199250 70 n RB407 38 ND 2708 18 50 116500 amp 24 BADE 7b NO 2584 210458 17po 36 201 25 268 30 315 28 385 32 1782 50 2338 9 2 amp 7 336b 64 453 0 194540 1850 50700 giri 00 56 45 75 00 8300 90 00 105 00 110 00 15300 153 00 57 5b 8r 00 int DD 124 00 141 06 17700 140 10 t185 0D 203 00 1 000 5760 649 OF 723 Of 1770 f Reti Greer SSESSRY SSRNSs Dg SSISJEBEERRAEE R 21 5 8C 50 R52 amp NU 8 86 R523 B NO 10 36 R52 6 ND R575 GAD 1
248. r own bright high paving future as an NRI trained computer service technician The biggest growth in jobs between now and 1995 according to Department of Labor predictions will occur in computer service and repair where demand for trained technicians will double There is still plenty of room for you to get inon the action if you get the proper training now Total computer systems training only from NRI To learn how to work on computers you have to get inside one And only NRI takes you inside a computer with total systems training that gives you hands on experience with computers peripherals and software As part of your training you ll build a Sanyo MBC 550 2 which experts have hailed as the most intriguing of all the new IBM compatibles The Sanyo even surpasses the IBM PC in computing speed and graphics quality Even if you ve never had any previous training in electronics you can succeed with NRI training You ll start with the basics rapidly building on the fundamentals of electronics until you master advanced concepts like digital logic microprocessor design and computer memory You ll probe into electronic circuits using the exclusive NRI Discovery Lab and professional Digital Multimeter that you keep You ll assemble Sanyo s intelligent keyboard install the power supply and disk drive and attach the high resolu tion monitor all the while performing hands on experiments and demonstra ti
249. re interconnected in such a way that incrementing and decrementing counting operations are not achieved Instead the connections are such that the binary word stored in the counter is shifted either to the right or to the left That is as each clock pulse occurs the bit stored in one flip flop is shifted into the flip flop next to it A common 4 bit shift register is illustrated in Fig 14 All of the clock T inputs are connected together to a single line Periodic clock signals are applied to that line The normal and complement outputs of one flip flop are con nected to the J and K inputs respectively of the next flip flop In sequence A single input line is used for entering data into the shift register a bit at a time A shift register is used to deal with serial data words A LSUDDD ORIGINAL STATE IDEE 1ST SHIFT PULSE i fat spol of on 2ND Lite fe oe 3RD ce Fig 15 How serial data is entered into a shift register register a bit at a time That is illustrated in simplified form in Fig 15 The individual blocks represent each of the flip flops in the shift register All the flip flops are initially reset When the first clock pulse occurs the first bit in the serial pulse train at the input will be shifted into the first flip flop The binary 0 is shifted out of the D flip flop As each shift clock pulse occurs the next serial input bit is shifted into the register The first bit moves over to the B flip
250. re waiting for you Cleveland Institute of Electronics Inc 7776 East 17th Street Cleveland Ohio 44114 216 781 3400 We believe in independent study because it puts you in a classroom of one So you can study where and when you want At your pace not somebody else s And with over 50 years of experience we ve developed proven programs to give you the support such study demands Programs that give you the theory you need backed with prac tical experience using some of the most sophisticated electronics tools available anywhere including our Microprocessor Training Laboratory with 4K of random access memory Of course if you ever have a question or problem our instructors are only a phone call away A half century teaching electronics ee NNI RP 35 Cleveland Institute of Electronics Inc 1775 East 17th Street Cleveland Ohio 44114 YES I want to learn from the specialists in electronics CIE Please send me my FREE CIE school catalog including details about CIE s Associate Degree program plus my FREE package of home study information Print Name Address re ae Zip Age Area Code Phone No j Check box for G I Bill bulletin on educational benefits Veteran JActive Duty MAIL TODAY HANDS ON ELECTRONICS N 2 ELECTRONIC NENTS MANUFACTURERS OF QUALITY ELECTRONIC COMPONENTS e BATTERY CLIPS amp HOLDERS e CABLE SETS e CONNECTORS e CAPACITORS e DISPLAYS e LEDs e F
251. registers can be created by simply cascading available 4 and 8 bit devices For example a 32 bit shift register can be created by simply cascading four 8 bit circuits Very large LSI shift registers are also available for special applications For example a 256 bit shift register made with MOS circuitry is available for memory applications Such a register is not used to store a single 256 bit word Instead it is used to store many smaller words For example a 256 bit shift register can store 256 8 32 bytes Those bytes are retained in the shift register flip flops end to end as illustrated Continued on page 1051 prep ORIGINAL STATE m be 1ST SHIFT PULSE 3RD Fig 16 How serial data is pup epu nnn 4TH removed from a shift register BD 4TH HE INSIDE THE s OSCILLOSCOPE Using the oscilloscope is not difficult when you know how We look at some simple application rules that will help you get almost all scopes up and running in no time By Marge Gustafson Larry Johnson and Carl Laron ONE OF THE n you can own jiliar with os you are using and to its best ierienced user complex than ch electronics lon there is a opes currently of the rules of gt chniques that and running more sophisti ind success liar unit the it to warm up important pur nimum when it gives you a ual and famil idiosyncrasies P x ume and head
252. rm into just about any thing requiring sound Even for Morse code andit sfun to learn LED Counter Module echan ode ion to the wor in EM ed circuits 795 Cat K 2639 450 Cat K 2623 has finally been converted to electronics And you don t have to find any King George pennies Simulates the throw the spin and the final result Come in spinner Cat K 2661 9 95 And this usetul counter can be used for a huge variety of counting applications or just for tun Wireless Mic Just like Ng pugs used in 50 Mini Spy movies Transmits to any standard FM ado in 6 Stereo Amp another room or next door dm You can really hear it all Pocket Transistor Radio Building this small set will 795 teach you a lot about the Cat K 2627 Cat K 263 Want an amplifier for your walkie stereo or radio Don t be tied to phones use this project and listen in comfort Or you can build this into a mini PA amplifier Cat K 2667 4495 fundamentals of radio And then you ll have fun using it too IRCLE 716 ON FREE INFORMATION CARD At the consumer end of the line the DC You weren t very specific but heres C mon Guvnor leave the auto alone That s the Fun Way 3 Minder telling vil gt y CN s losing 8 US whic now X3 Australia s national game TOLL FREE 1 800 332 537 Auto Battery Alternator Monitor Update Recently a reader who had built the Auto Battery Alternator Mon
253. rminated no standing waves then an SWR of 3 to 1 will add a further I dB loss The graph in Fig 2 indicates the additional loss for a wide range of basic cable losses and SWR values At 450 MHz using RG 8 U cable with a run approaching 30 meters a loss of 3 dB could be expected and if it had to be tolerated than anything which would minimize further losses would be worth considering That is a case where all else being equal correction at the antenna might be preferable to that at the transmitter At lower frequencies losses become less important At 150 MHz RG 8 U wastes only 2 dB 30 meters an additional 0 8 dB for a 3 1 SWR and a 30 MHz 0 9dB plus 0 48 dB for 3 1 SWR So hopefully that should put the SWR problem into some kind of perspective But there are other misconceptions which we might perhaps comment upon One is that the reflected energy finds its way back into the final stage and overheats it Wrong It is true that a transmitter working into a transmission line with a high SWR may show signs of distress But the distress is not due to the SWR rather it is due to the incorrect load at the antenna into which the transmitter is trying to work Cable Length Another popular untruth claims that the length of the cable is critical that it must be an exact multiple of a half wave length long if the transmitter is to be properly loaded and the standing waves eliminated even when the antenna is present ing a pro
254. rol simplifies set up Stable hands off triggering P P AUTO detects sig nal peaks then sets the trigger level for you Dis play asynchronous signais using VERT MODE trig gering Indepen dent TV field and line selection Front panel laid out by function for ease of use Color coding aids the user in opera tion Functions and modes are placed logically All nomenclature is Clearly labeled and protected behind a scratch tess Lexan surface Our direct order line gets you the industry s leading price performance portables and fast answers from experts The 60 MHz single time base delay 2213A the 60 MHz dual time base 2215A and the 100 MHz dual time base 2235 offer unprecedented reliability and affordability plus the industry s first 3 year warranty on labor and parts CRT included The cost just 1275 for the 2213A 1525 for the 2215A 1750 for the 2235 7 Even at these low prices there s no scrimping on performance You have the bandwidth for digital and analog circuits The sensitivity for low signal measurements The Sweep speeds for fast logic fami lies And delayed sweep for fast accurate timing measurements All scopes are UL Listed and CSA approved You can order or obtain literature through the Tek National Marketing Center lech nical personnel expert in scope applications will answer your questions and expedite delivery Direct orders include comprehen sive 3 year warranty
255. ronics Skills you need lg RECEIVER CHARACTERISTICS technical details and specifications along with examples of actual receivers built at comparatively low cost ll ANTENNA DESIGN and exactly how you can build a spherical antenna while keeping total earth station cost for the complete system under 1 000 E THE FRONT END is critical when you build your own system We help you explore several different approaches to so designate on then device 3 off Perform steps I through 3 above Dial device I on Dial 0 off 2 3 4 Dial 3 device 3 5 Place telephone on hook NOTE Steps 2 through 4 should be performed within 15 seconds after step 1 That s all there is to it Your Telephone Remote Contro System is up and running and so are your BSR remote making one that will work for you E RECEIVER SYSTEM hardware and how it goes together to bring you direct from satellite TV reception in your own home To order your copy Complete coupon and enclose it with your check or money order for 7 00 plus 1 00 for postage and handling We will ship your reprint within 6 weeks of receipt of your order All others add 4 00 for postage New York State resi dents must add 58c sales tax OP Please print Satellite TV Repnnts i 45 East 17th Street Electronics New York N Y 10003 Name i wa
256. rpreted by the constructor or the matching device if one is used may be incorrect Alter natively the cable impedance may be other than that claimed There is the story about the dishonest electronics surplus dealer who could supply either 50 ohm or 75 ohm cable at a very attractive price both off the same reel In other words when the SWR meter indicates that there 1s something wrong the important thing is to make a systematic approach to finding out what it is For example terminating the cable in a good dummy load having the same resistance will quickly indicate whether or not the cable is at fault If it is not the antenna is the next obvious suspect Exactly what needs to be done or can be done to change the antenna s impedance will of course depend on the particular type of antenna and what is physically convenient or practical But whatever the approach the SWR meter can be used to monitor the effect of the changes or adjustments that are required Finally one more controversial point Just where should the SWR meter be connected in the line at the transmitter end or the antenna end Some authorities are adamant that it should be at the antenna end while others are equally em phatic that the precaution isn t necessary While in theory it can be shown that the antenna is the right place to make this measurement the practical situation is that that is seldom a very convenient or even feasible arrangement So in
257. s 1981 4 00 Jan Feb March Dec 1981 not available Write in issues desired Etch your own PC boards 83 00 Hands On Electronics 1 lt tna wes 4 00 Hands On Electronics 2 94 00 J Hands On Electronics 3 4 00 Hands On Electronics 4 060 05 3 50 Hands On Electronics 3 9 vv acta 2 50 VCR MPDSIS erre een henge RAS 3 00 IBM Typewriter to Computer Intertace 3 00 To order any of the items indicated above check off the ones you want Complete the order form below include your payment check or money order DO NOT SEND CASH and mail to Radio Electronics Reprint Depart ment 200 Park Ave South New York NY 10003 Please allow 4 6 weeks for delivery Radio Globo 11 805 kHz Radio Band eirantes 11 925 kHz and Radio Record 11 965 kHz From Colombia one of the strongest and the most consistent signals is that of Radio Sutatenza operated by a Roman Catholic agency although its program ming is not typically religious in tone You ll find that Spanish language station quite easy to hear since it is all alone on its 5 095 kHz frequency most of the time mornings and evenings Radio Nacional de Chile from Santiago operates on two shortwave frequencies REPRINT BOOKSTORE C Special Projects 4 Summer 1982 4 50 C Special Projects 5 Winter 1983 4 50 Special Projects 6 Spring 1983 4 50
258. s the relationship between dial pulses ring pulses and on hook off hook Those are the signals that the microprocessor uses to determine telephone line activity Any connection to the phone line is controlled by the FCC Part 68 and your local telephone company Since each tele phone company may have its own rules I suggest you contact yours before making any connections In general the FCC is concerned that no harm or disturbances of any type may occur to the telephone line All connections to the telephone line must be made through standard plugs or jacks In that way the device can be easily disconnected if suspected of causing an interference problem The Telephone Remote Control System has been designed to meet those require TABLE 4 UNIT NUMBERS AND COMMAND CODES Unit Number Command Code g i Bit Pattern E ALL UNITS OFF ado ALL LIGHTS ON 00041 ON 1 4 BIT PATTERN AC CYCLES Sat HOUSE CODE A IDENTIFIER Fig 4 This diagram shows the bit patterns and where they occur during the AC cycle Note that the house code is pre ceded by a four bit sync identifier 1110 That pattern is transmitted as three bursts of 120 kHz with a duration of 1 milisecond during half cycles of 8 3 milliseconds with the zero indicated as an absence of the 120 kHz burst during the final half cycle The total time of that transmission is about 32 milliseconds The house code on the other hand is trans
259. s appliances rated at up to 15 amperes or 1 3 HP AC motors or 500 watt lamps on and off One remote control module is required for each lamp or appliance that you want to control When the Control System is used to control appliances an extra precaution should be taken For example if an electric heater is turned on by remote control while clothing is draped over it a fire could result Please keep that in mind and be alert to potential problems like the one mentioned That will help you get the most convenience and pleasure from your Control System More than just another remote control system this project makes use of existing telephone installations in your home to manage the modules and switches in your BSR 10 system 986 d34d NYT o wo HANDS ON ELECTRONICS e TABLE 1 SWITCH SETTINGS FOR HOUSE CODES FT TIL am ar ENIGSTI Switch 5 ambu E mm HE rt aired Ea HOUSE Gode About the System The Telephone Remote Control System is under micro computer control and requires some minor programming prior to use The system is equipped with a seven bit switch to eliminate interference with numbers or area codes fre quently dialed and to avoid transmitting or receiving signals to or from a neighbor s system While referring to a photo showing the 7 section DIP switch S1 S7 select and set your own code as follows Each of the seven switches can be set in either of two positions ON or OFF To set th
260. s by re using the components and printed circuit board Each project comes with a circuit description circuit diagram component layout diagram parts list and construction notes All projects operate from a 9 volt battery making them a safe introduction to electronics for the beginner Multi circuit Board Projects published by Bernard Babani Publishing Ltd London England is available through Electronics Technology Today Inc P O box 240 Massapequa Park NY 11762 0240 priced at 6 00 including shipping and handling Basic Electronics Technology By Avis J Evans Jerry D Mullen and Danny H Smith Texas Instruments has published a one volume 464 page ready reference to semiconductor circuits and systems The book is an overview of electronics technology based on integrated circuits It explains simply and thoroughly both the basic concepts and By Barmard de Backus CIRCLE 725 ON FREE INFORMATION CARD the practical applications of electronic circuits and systems Engineers technicians students and technically interested consumers will all find it a valuable tool for learning and as review or as a reference Basic Electronics Technology covers most of the primary functions and associated circuits that go into the electronic systems that touch our lives every day It explains how semiconductors and circuits work as amplifiers and oscillators in power supplies audio systems AM FM radio TV and other
261. s the giant crystals until they are thousands of times longer than usually made LC OFC cable also makes use of a purer grade of copper known as oxygen free copper OFC Ordinary copper like the kind used in so called monster ca bles that are currently on the market con plus Match your uw de pro jar cells Whe trans Jes X pct contri TES d J o r IF YOU RE THE KIND OF READER that doesn t want to wait you can order your next copy of Hands on Electronics now Hands on Electronics is crammed full of electronic proj ects that you won t be able to wait to build for yourself You can expect top notch digital proj ects fun to play electronic games valuable add on computer projects BCB and shortwave vices to Improve your cars performance test equipment ideas and more in every issue of Hands on Electronics B TO HELP YOU TO BE SURE that you dont miss any future issues of Hands on Elec State Get every issue SUBSCRIBE TODAY Use the order form below or the Zxe ni 10 rse Ant we short c Circu r cal Me aA Co V cones ni aes Budge you rent miter receivers photographic darkroom gadgets de Hands on Electronics SUBSCRIPTION want to be sure don t miss any issues Send me the next six issues of Hands on Electronics for Hi B 14 00 Postage is free in U S For Canada add 3 00 Foreign add 7 00 d i want to be sure
262. scratching later when you get down to work But surprisingly that step is often overlooked especially by so called experi enced users Once the unit has warmed up sufficiently the next step is to obtain a trace Be sure that the trigger mode is set to AUTO MATIC and the trigger source is set to INTERNAL Then select a medium sweep speed using the TIME BASE control often labeled TIME Div or something similar Set the HORIZONTAL and VERTICAL trace position controls to about midrange and adjust the INTENSITY control until the trace appears If at full intensity no trace appears see if one edge or another of the CRT appears lit or glowing slightly If so that gives an indication that the trace is positioned off screen in the direc tion of the lighting Use the LEFT RIGHT and UP DOWN position controls to move the trace so that it can be seen near the center of the display If you can not find the trace by using that technique the following systematic approach can be used Set the HORIZON TAL position control fully counterclockwise Now rotate the HORIZONTAL control a small amount in the clockwise direc tion and then rotate the vERTICAL control through its entire range Rotate the VERTICAL control slowly or the trace may shoot across the CRT display screen too rapidly to be seen Repeat that procedure until the trace is located Displaying a Waveform Once the trace is obtained set the position controls such that the trace is cen
263. sed in the IBM PC AT a hard disk provides a more practical and cost effective answer to greater on line disk storage for con ventional personal computers A Magnetized Surface Hard disk is a generic term for any kind of mechanism that uses a rigid metallic disk with a magnetic coating As far as the user is concerned it doesn t make any difference what the specific coating mate rial is as long as it can store magnetic information in the same manner as a con ventional floppy disk Although there are several different kinds of hard disk mech anisms on the market because of their reliability and unusually low retail price the most popular is a design known as a Winchester Winchester is IBM s internal code name for the particular mechanism when it was being developed More Storage Hard disk drives provide greater stor age capacity because of the way in which the device is built Because the disk i5 rigid it has a more precise surface in relationship to the read write head which permits a denser track count And for the same reason it can be rotated at more than ten times the speed of a floppy disk Since the amount of magnetic information that can be written to a disk is proportional to the speed of the disk the hard disk can store more data per unit of track than a floppy The most modern conventional sealed hard disk drives generally con tain one or more internal disks As a rule of thumb the latest and most
264. separate currents flow in the secondary each are identical to the other but opposite in phase That means that at any given in stant the two voltages are of the same magnitude but opposite in polarity One Is so many volts above zero while the other is an equal amount below zero a negative voltage If that sounds con fusing don t let it worry you Phase rela tionship is quite an involved subject it will all come to you eventually What those out of phase currents do however is the secret behind this type of audio amplifier circuit Audio signals are alternating current that is they follow a fixed cycle On the first half cycle the voltage from the top end of the trans former might be going positive and the voltage from the bottom end going nega tive In the next half cycle the roles are reversed the top end goes negative while the bottom end goes positive As you may remember an NPN tran sistor needs to have a positive voltage of at least 0 6 volt or so applied to its base before it can conduct Obviously if the voltage from T1 is negative during any half cycle the transistor does not con duct But during the next positive half cycle the transistor that was off turns on as the waveform swings positive and vice versa In fact R4 and DI keep the transistors just about conducting so that the moment the signal voltage swings positive they conduct immediately Because each tran sistor can be driven har
265. series connected But the other input fed directly through C2 to the timer circuit IC1 is wired in parallel thus the builder has a choice of wiring schemes of parts is available from the supplier given in the Parts List You may also choose to etch your own circuit board or build the circuit on experimenters or per forated construction board The choice is yours Once you have everything that you need construction can begin Mount the components as shown in the parts placement diagram Fig 2 solder the resistors and capacitors first taking extra care to mount C3 and C4 the two tantalum units the right way as they are polarized The small sign marks the positive lead positions Make sure that all the components are positioned neatly and correctly dressed before soldering them in Next position and solder RLY after ensuring that you have it correctly ori ented that is simplified by its five pins which only line up one way Moving right along position diodes D1 and D2 taking care to see that they are correctly polarized Remember the cath ode K is the banded end and corre sponds to the bar in the circuit diagram Solder them in taking care not to overheat them TRI is next care must again be taken to ensure correct polarity with the base connecting to Cl Solder the tran sistor in using a heatsink to prevent damage from overheating The 555 timer ICI is the last compo Fig 2 By follow ing
266. sh of test equipment to the marketplace to help both users and TV service technicians do telephone repairs Unfortunately professional test equipment often costs more than a new telephone yet it doesn t do much more than our Quickie Telephone Line Tester which incidentally can be built for just a few dollars About The Circuit The Quickie Tester which consists of only two elec tronics components see Fig l tests the polarity of the telephone jack s wiring the presence of sufficient voltage to run the telephone the telephone s off hook loading to determine if the telephone is really connected and ringing voltage To use the device you need only plug it into a telephone s modular jack If the jack is wired correctly the Quickie Tester will emit a green glow If on the other hand the jack s connections have been reversed the tester glows red Either way if the tester glows the line is alive If you want to check the telephone instrument itself first install a two set modular adapter on the wall jack That adapter is available at most electronics parts outlets and variety stores you ll even find them in supermarkets Con nect the Quicky Tester to one socket and the telephone to the other After the tester glows to certify the line is alive pick up the telephone s handset placing the telephone off hook If the telephone connects to the line the Quicky Tester s glow will extinguish if it doesn t the te
267. signal that has not been rejected by the tuned circuit then passes through a diode detector D1 The detector chops off half the waveform otherwise the two halves would cancel each other out The clipped waveform which contains all the audio information micro switches thermal switches metal lic window tape etc may all be used in the loop The important thing to re member is that all normally closed de vices are connected in series In the normally open loop see Fig 5 such things as pressure mats panic switches trap switches etc are con nected in parallel If the circuit is to be use as a car Alarm it will require the certain components be left out the modified schematic diagram is shown in Fig 6 Remember that whatever Alarm device you choose it should have its own battery back up if operated from an AC adaptor i is then fed to the first of the amplification stages Along the way the RF component of the half waveform is filtered out as it s no longer needed leaving only the audio signal ICI is of a type normally regarded as a digital having found its greatest use in digital circuits such as computers and is used in a completely different way than normal In our circuit we use it as an amplifier That unit consists of four indi vidual circuits we re using only three Each one increases the level of the signal until the final stage where it has been increased to a point that s sufficient to dri
268. sily removed from the drive mechanism That kind of design permits almost unlimited hard TOTAL PAGES 50 each TOTAL PRICE disk storage because a fresh hard disk can aie GT eae DEG Roda Geen dt eee Can EIU be quickly substituted for a full disk Of t course the removable hard disk has the I MAIL TO Radio Electronics gt same disk swapping limitations of a flop y Reprint Department 200 Park Ave South New York NY 10003 All payments must be in U S funds py disk if some of the desired data is on t Total price of order re MEN l js gy Sales Tax New York State Residents only o arar n esee e one disk and the remainder on another Shipping amp Handling U S amp Canada only Includes FIRST CLASS POSTAGE 1 00 per item i But because hard disks can be substituted All other countries 2 00 per item sea mail nere at will it s just as easy to group related 4 4 00 Der itemi alt Mall oou eo tero 9x Rr ger eko eee ogee D software and data files on the hard disk as 5 A jd tia oaa on E TEE E emee deed oe ee secs 1 it is on a floppy zr MAU Although the marketplace is overflow T i I EE D gt t Name i ing with various kinds of surplus 5 14 inch O address hard disk units and complete upgrade kits N i i di i A city State Zip for non cartridge hard disk drives the 10 Z 14 i MB hard disk is unofficially recognized as L E ucl c SP am ems cns M Ge zum GUB ns ER UH ess UN
269. t or suck it and see approach SWR Meters One such approach involves the use of a standing wave ratio meter or SWR meter But it would be premature to go into details at this stage We need to talk about SWR in some detail first So far we have considered only those situations where a resistor or an antenna which looked like the same re sistor was connected directly across the transmitter output terminals Apart from a few special cases feeding an antenna in that manner is not very practical We need to locate the antenna as high as possible and clear of objects which might NT Till eri shield it while we need to put the transmitter in a convenient indoor working location some distance away Those prac tical considerations are always self defeating however thev can be minimized And to couple the two together we need a special kind of cable one that will convey the transmitter output to the antenna with minimum loss and which in itself will nct radiate any significant amount of that energy into a shielded environment where much of it would be wasted There are two types of cable commonly used by amateurs the open wire line and the coaxial cable The open wire line can be homemade has very low losses and can be made to have any impedance characteristic over a wide range On the other hand it can be awkward to install and 1s much less popular than it once was Coaxial cable is a commercial product with somewhet
270. t stage Another possibility again depending on the output stage design is that it would try to deliver more than its rated power but run into overload in the process and destroy the Output circuit and other circuit sections as a result For tunately most commercially designed transmitters are well protected in this regard but there is no point in taking unnecessary risks Original story appeared in Electronics Australia November 1984 edition and reappears here by permission But that risk aside we should make every endeavor to present the correct load to the transmitter simply to ensure that it delivers the maximum power for which it was de signed On the other hand there is little to be gained by simply feeding that energy into a resistor it will radiate very little of the RF energy and waste virtually all of it as heat So we replace the resistor with an antenna and fairly obviously this antenna should look to the transmitter like a 50 ohm resistor if it is to deliver maximum power Assuming the antenna is resonant at the transmitter frequency and fed at the right point it will look like a resistor If it is not resonant it will exhibit either a capacitive or inductive component ac cording to which way it is off resonance Assuming that the antenna is resonant the next question concerns the value of resistance it presents to the transmitter And this is where the going gets tough because in other than a very few
271. tected interface a point between the tele phone company s wiring and wiring in your home If you cannot disconnect your wiring from the telephone network you may be exposed to hazardous voltage during installation KITCHEN LIVING ROOM BEDROOM MOQULAR JACK MODULAR JACK e PHONE LINE IS CUT MODULAR JACK HERE MODULAR JACK e dif E x ms CORO WITH JACK AC POWER BASEMENT LABELED OUTPUT 4 CORO Tu g TELEPHONE REMOTE CONTROL SYSTEM PROTECTED INTERFACE CORD WITH JACK LABELED INPUT Fig 10 To connect the Control System to a multiple phone installation is similar to that of the single phone installation except that the input to the Remote Control is connected to the main feed in and the output feeds the in house telephone network and you should use a professional installer Never attempt that work during a storm l Find a place close to an AC outlet 2 Cut the phone line with an insulated handle wire cutter 3 Carefully strip back the outer telephone wire jacket about 3 inches on both cables then remove inch of insula tion from the individual wires 4 Install two modular phone jacks with standard wir ing blocks Next connect the two cables one at a time to the two wiring blocks Connect the 4 color coded wires to the corresponding screws on the wiring block It your house wires do not match you probably have a 6 wire network and should use the color codes specified in Table 5 Use an existing
272. tem modular phone plug la belled output into existing telephone base If telephone cord is permanently attached to the phone an in line coupler that inter connects two modular phone line cords will be required They may be purchased at your local phone compa ny or electronic parts store 986 daa NV J HANDS ON ELECTRONICS J eo MODULAR JACK B MODULAR PHONE PLUG MODULAR INPUT PHONE PLUG QUTPUT W EXTENSION PHONE TELEPHONE REMOTE CONTROLSYSTEM Fig 9 The installation of the Control System AC POWER in a single phone system is as easy as one RD two three The control circuit is placed between the existing phone installation and the phone company network and then plugged into the nearest AC outlet as shown 4 Insert the plug of the Control System s AC power cord into a 117 volt AC outlet Multiple Telephone Installation The Telephone Remote Control System installation allows any phone connected to the line to be used to turn lights and appliances ON and OFF using one Telephone Remote Con trol System Refer to Fig 10 The installation is similar to the single phone installation except the Control System is in stalled at the feed in point where the telephone line enters the premises This installation involves working with wire and jacks which carry an electric current Telephone jacks or wires must not be installed unless you first disconnect the in house wiring at the pro
273. tered vertically and begins at the left side of the CRT Obviously if a waveform is to be displayed a signal must be input to the scope That is done usually via a front panel vertical input connector Next depending on the type of measurement you are making the VERTICAL INPUT switch should be set to the appropriate setting AC or DC Set the vertical attenuator control labeled voLTs Div or some thing similar so that the entire waveform can be displayed over one half to three quarters of the screen height If you are unsure about the amplitude of the input signal select the highest attenuation setting Once the trace is displayed the TIME BASE control should be set so that a few cycles of the input waveform can be seen Note that the trace may not be stable at this time If not the triggering level control will need to be adjusted to lock in the display For accurate measurements be sure that both the TIME BASE and the VERTICAL ATTENUATOR controls are used in their calibrated modes Triggering Most scopes have two triggering mode switch settings AUTOMATIC Or AUTO and NORMAL Automatic triggering is the most frequently used setting In that mode a trace is displayed even when the signal level is too low for triggering In the AC coupled automatic trigger mode a trigger sig nal is generated when the displayed waveform passes through the O volt point of the AC portion of the input waveform Because of that the automatic mode
274. ters up to 3 milliwaits ar mare Phase culi Zor pris Hadar Detectors e ii recused arose eese thal fe riimted sa ai nothing is readily visable Io milher the police ur thieves A tashi aset Mn did d Abra TO hires mid ah Jeremie ri palits agree with Mator Tred acad Acpogeek that Ver ER SP CTRUM is the best detector available amd we know of n coker nemore afe icti chat js even Im che mie LEAGUE as iie SPECTRUM REMOTE Ciroer he Desi for youtsetf Howe I Maths abicady medified for direct cnemection to the ORDER TODAY M NEY HACK GUARA D Complete Literature amp Plans Pep LI Set al Comit Boards QE LT X and K hond Mcruwave Cscilbrers Treaster Cal Whistler Spectrum mectied for i irn dammer 259 00 E Wet POEL CUAL Fart joe Hf kay a 251 AMI E MineiFy vener Spectrum for use w jammer o 85 00 CALL or send the following information Noms COhdered a Numero 8 elress Payment Check Mowe Order VISA ar MC card number expirution doce and sigmaburel sE it EFE Crogan Manisa lir z EHE XS Barbar Blvd pm Forland DE 07219 ORDER LENE S03 624 8104 EF rrr iy F kiij desir Disigi Ca k CIRCLE 715 ON FREE INFORMATION CARD PP Sn e t Take A a stocka x in Ameri ica ADVERTISING INDEX HANDS ON ELECTRONICS magazine does not assume any responsibility for errors that may appear in the index below Free Information No Page 709 All Electronics ue DOES S 711 AMC Sales NETS TORRENS Lc
275. th Your Timex Sinclair shows you how to build creative electronic projects in your home Beginning with the basic the author clearly explains all the wiring techniques and components you ll need to control external devices with your computer You ll learn how to CIRCLE 731 ON FREE INFORMATION CARD construct simple yet powerful control circuits build an interface connector assemble a weather station build your own robot construct a speech synthesizer for your robot and more The text will help you develop a solid Continued on page 18 SLOWN any GOOD IA Pc TRACES ATELY THEM FAST WITH CIRCUIT FIX The CF 1 CIRCUIT FIX KIT lets you repair or modify printed circuits in minutes Just put an adhesive copper foil sheet in the patented clamp and cutter guide adjust the trace width O13 minimum and cut a perfect copper strip every time Kit includes clamp guide knife copper foil 154 assorted diameter donuts and instructions The CF 1 is stocked by many electronic parts distributors or order direct Price includes shipping Minimum order 20 00 NJ and CA residents must add state sales tax to order total GFE 1CIRBGUIT EIX KW 6 2 a ee borg 6 ntu 23 50 CF 2 306 Assorted Adhesive Copper Donuts Nea ae 4 30 CF 3 2 Sheets Adhesive Copper Foil 34 x 10 2e 4 30 DATAK S COMPLETE CATALOG lists hundreds of printed circuit products and art patterns Also contains dry transfer letter sheets
276. th edition 13 95 Latest info on usual and exotic shortwave broad cast stations 25 SIMPLE AMA TEUR BAND ANTENNAS 5 00 A kinds of antennas for all kinds of amateur radio reception maai PRACTICAL ELEC TRONIC BUILDING BLOCKS Book 1 5 75 Build the blocks and then combine them to iorm almost any custom project of your Choice MICROPROC ESSING SYSTEMS AND CIRCUITS 7 50 Guide to the elements of microprocessing sys tems Teaches all the tundamentals Book t IC PROJECTS FOR BEGINNERS 5 00 Written especially for the ess expenenced experi menter Complete parts laycuts and wring di agrams 555 PROJECTS 5 00 So usefu that this IC has an unparalleied reputation Heres a book full of usefu app ications Total Price Ol BOOKS es eee ee ee Name Sales Tax NY State Residents 22 20005 Aadress Shipping in U S only City x State Zip 1 00 1st two books 40c ea additional Canadian Shipping 1 50 1st two books 50c ea additional JOIAC ENCLOSED S035 iru eere S Ub trn d PLE es eaa Cer a pa Ee RADIO DXiNG 5 00 How to optimize the reception of distant Short wave broadcast and amateur stations INTRODUCTION TO RADIO DXING 5 00 Get into this fas cinating hobby This book tells you just about every thing you need to know to get started PRACTICAL ELEC TRONIC BUILDING BLOCKS Book 2 5 75
277. that the voltage measured at those terminals is 3 6 That suggests an internal pull up resistor connected to the output terminal see Fig 4 If that is so and the device is a quad gate which seems very likely tH MM M j Th SR SK TQ Ju R am Fig 3 Signature chart for a TTL 7400 quad 2 input NAND IC All but a few TTL IC s have this typical two row signature there should be four identical re sistors to V one from each output And that implies we should read twice the pull up resistor value be tween any two outputs In that case the circled 7000 ohm values in the signature point to 3500 ohm pull ups in each output With a V of 3 6 dm Ne volts applied grounding any output NCMO M through the current meter should 20d p cause a current flow of just about 1 EE mA And that s what we got List the i outputs and inputs on the signature chart Step 5 The symmetrical pattern of resistances in the signature and the strong evidence for four independent outputs with logic level voltages pretty much rules out any linear IC Resistive pull up could be DTL but DTL inputs are active low and our IC is active high After reviewing all the evidence I felt there was absolutely no doubt that this device was RTL That conclusion was recorded in Fig 2 Step 6 We now manipulate the inputs and observe the output responses to determine what kind of logic device we have Wit
278. the plastic tubing up the wire to the LED It takes about 15 minutes to assemble the device yet it can easily save a 50 service charge the next time your telephone fails to work 9861 H3d3 NVTC o HANDS ON ELECTRONICS o POWER SUPPLY BALANCE INDICATOR By J Daniel Gifford If you re into circuit testing or design using integrated circuits which often require precision split power supplies then this little balance indicator is for you JA SPLIT POWER SUPPLY ONE WITH BOTH POSITIVE AND Negative outputs is often a necessity when working with many types of linear or digital integrated circuits Most such C s and their surrounding circuits require that the two halves of the supply be equal to each other within a few percent When you test or design such circuits if the positive and negative supply levels differ by a significant amount the circuit can malfunction or even self destruct The signifi cant amount is a function of the IC s characteristics that appear in the part s specification sheet prepared by the man ufacturer Unless you are fortunate enough to own a split power supply with a precision meter for each side you know that it s difficult to get and keep both sides in perfect alignment You must either rely on a single built in meter switched between the positive and negative outputs or use a digital multimeter DMM or volt ohm meter VOM to carefully set each level Both methods are
279. the integrated circuits note that they all face in the same direction Be especially careful when install ing the diodes and electrolytic capacitors Observe the polar ity of those parts as referred to on the pictorial diagram in Fig 8 Transformer Tl has a red dot located on one side and should be installed near terminals El and E2 Pulse trans former T2 s pin numbers are marked on the underside and careful attention should be observed during its installation The AC power cord connects to the circuit board at connec tion points El and E2 The alarm feature if desired is connected to E7 and E8 A short applied across those two BU NT 1 RING 2 HK DIAL PULSE1 gt e T I uU Hook Fig 5 This diagram visually illustrates the ring signal and dial pulses that normally occur during the on hook and off hook condition of the phone It is these signals that are used by the microprocessor to determine telephone line activity j ne PULSE2 H 9861 B3d NVf n HANDS ON ELECTRONICS J oO b qd m o Fig 6 The Control System is built on double sided printed circuit board which makes for a less cumbersome finished unit The printed circuit foil patterns for the component side of the board is shown it is to be used in conjunction with the foil pattern of the solder side of the board shown in Fig 7 Fig 7 Since the Control System is built on a double sided bo
280. them however seem to be unlicensed Almost all of the Peruvian stations are broadcasting to domestic audiences For that reason most signals are not as power ful as those from other countries and there is no English programming to be heard Here are some DX opportunities for you 4 790 kHz Radio Atlantida in Iquitos 4 885 kHz Radio Huancavelica in the town of the same name 4 990 kHz Ra dio Ancash 5 199 kHz Radio Imagen 6 115 kHz Radio Union and 6 188 kHz Radio Oriente On a number of those Peruvian sta tions you ll hear huayno selections the typical music of the Andes You ll quickly peg it as the sound duplicated a few years back by Simon and Garfunkel on their recording of El Condor Pasa Venezuela s national shortwave voice Radio Nacional from Caracas broadcasts on 9 540 kHz plus at the moment a parallel 9 500 kHz frequency apparently a change from the former 1 695 kHz out let As with most of those South American SW stations the best times to try for them are the early morning hours about dawn and during the evening A favorite for music is another Caracas Concluded on page 106 Friedman on Computers Continued from page 98 tected by a filtered air supply from air ARTICLE bornes such as dust there are available for the latest generation of personal comput ers hard disk drives that use plug in disk em MT VEAR cartridges the hard disk Is enclosed in a plastic case that can be ea
281. then simply loon the lights RED HOOK UP LIGHT means that you have made an error in hook up No damage has been done correct the problem then continue RED EMITTER LIGHT means that the ground path for horiz output stage IS open Correct the problem then continue RED B OPEN LIGHT means that the primary LV supply in the TV set is open Correct the problem then continue No top row lights equals normal Look at the middle row of lights RED START UP LIGHT means that the start up circuit in the TV set is not working no start up pulse GREEN START UP LIGHT means the start up circuit in the TV set is working normally Yes it is 10096 accurate Even on Zenith s single pulse start up circuit RED HORIZ DRIVE LIGHT with a green start up light means that the horiz driver transistor in the TV is shorted E to C GREEN HORIZ DRIVE LIGHT means that the horiz oscillator and driver circuits are operational READ THE DC VOLTAGE METER THEN PUSH THE TEST BUTTON If the meter comes up to or falls back to factory specified DC collec tor voltage the LV regulator circuit is working If it fails to do SO it is not working RED B RUN LIGHT means that the B source that normally keeps the horiz osc driver circuits running after the start up B pulse has been consumed has become open GREEN B RUN LIGHT means that the B resupply voltage scan derived is being provided All is normal if all three l
282. ther hand to protect the files of an external hard disk you need only turn off its power switch Data that s needed at remote stations can simply be copied to the floppies In that way unauthorized users cannot muck around in your hard disk s files to steal or destroy data If ycu wanted to provide access to specific hard disk data while maintaining security ycu could copy it from the hard disk to a flop py A drive and then turn off the hard disk Users would then have access to only the data copied from the hard disk E NEW IDEAS is packed with 42 practical cir cuits for the Electronics Experimenter and Proj ect Builder In addition to the headlight alarm the voltage freezer and the remote telephone ringer you get complete plans for a simple Tesla coil project that can generate 25 000 volts AC and draw one inch sparks Other interesting projects are a sound effects generator a crys tal tester a stereo remote controi and much much more Each project was selected for its low cost of parts E WANT TO EXPAND your knowledge of elec tronics Build gadgets that only you can have on your block Acquire a library of projects NEW IDEAS is the gold mine of circuits you should own and read You could start the first night building a project that will have others praising what it can do and admiring you for building it E THERE ARE PROJECTS for everyone au tomotive household test equipment audio and hi fi and proje
283. this little circuit T av TO d 12V into the latest in electronic jewlery The BATTERY board has been designed to wear as a m Fig 1 The circuit is really poH ES p acan xb pay 220 id simple and the only problem S Dn E MS S y A O that might be encounted has to 3 do with the polarity of the m How It Works components Over half of them When power is applied refer to Fig 1 are polarized It will operate capacitors C and C2 start to charge to the from a very wide voltage range amp oi e3 HANDS ON ELECTRONICS go gt supply voltage via the base emitter junc tions of TRI and TR2 That charging cur rent tries to turn both the transistors on But both cannot turn on at the same time as we will see in a moment By a com bination of component tolerance one of the two transistors will turn on first By the time the transistor has turned on let s assume it to be TR1 the capacitors have reached a reasonable state of charge They could have quite a few volts across them So the positive end of the capacitors would be a few volts positive with respect to the negative ends As you can see the positive ends of the capacitors are connected to the transistor collectors with their negative ends to the opposite transistor s base When TRI turns on its collector voltage drops to a low level probably around volt But wait the capacitor connected to that point has a potential of 6 volts What happens here Because the capa
284. tically turn all lights on when the existing in house alarm system was en abled The lights would remain on until the alarm system was secured or reset All of the above has been implemented in what call the Telephone Remote Control System T Hs By Ronald J Dale How It Works The Telephone Remote Control System is used with the standard telephone and remote control modules like the ones listed below The Control System may also be used in Conjunction with an existing alarm system to turn on all lights when the alarm sounds The Control System operates when the telephone is taken off hook and a pre programmed access code is entered followed by the device number to be turned on or off The Control System transmits control signals over existing house wiring to remote control modules Those sig nals cause the remote control modules to turn lights and appliances on and off Feur types of remote control modules exist that can be used with the Control System They are Wall Switch Module Replaces standard wall light switch It is capable of switching incandescent lamps rated at up to 500 watts on and off Three way Wall Switch Module Replaces 3 way up siairs downstairs switches It turns incandescent lamps rated at up to 500 watts on and off Lamp Module When plugged into a wall outlet it turns incandescent lamps rated at up to 300 watts on and off Wall Receptacle Module Replaces the standard wall receptacle It turn
285. tly or through some resistance when reading forward resistance from substrate to V V in linear IC s that multiplicity of paths will give a lower reading than any other terminal on the IC Thus it is possible to identify the V terminal 9861 H34 NVf e HANDS ON ELECTRONICS Telephone Remote Control System Continued from page 79 2 Dial 2 first number of the access code 3 Dial your pre programmed access code 4 Dial 9 all lights on 5 Place telephone on hook Let s turn all the control modules off 1 Perform steps 1 through 3 above 2 Dial 0 off 3 Dial 9 all control modules 4 Place telephone on hook Let s turn device 1 could be any appliance or lamp you Satejjite WHAT TO KNOW BEFORE YOU BUY SATELLITE TY BASICS WALL ABOUT SATELLITE TV DISHES X TURNKEY SYSTEMS HOW TO INSTALL A TVRO SYSTEM Ll Don t miss out again Send away today for your 48 page book let containing a complete reprint of all seven articles in the series on Backyard Satellite TV Receivers by Robert B Cooper Jr This ali inclusive report gives you all the data you need to build your own Back yard Satellite TV Receiver B TELLS ALL ABOUT domestic satel lite communications with full details on how you can pull those elusive TV sig nals from space WB LEGAL REQUIREMENTS technical specifications and how you the home constructor can meet them Find out what mechanical and elect
286. to the counting chain Each additional flip flop lengthens the binary word of the counter by one bit thereby doubling its maximum count capability The total number of states that a counter can assume is 2 where N is the number of flip flops With 4 flip flops the total number of states is 2 2 X 2 X 2 x 2 16 Those states are 0 0000 through 15 1111 You can determine the maximum count capability of Ui counter with the simple formula shown below M 2N where M maximum count number and N number of flip flops With four flip flops the maximum count capability is M 24 1 2x2x2x2 1 M 16 1 15 A 5 bit counter has a maximum count capability of 31 A 6 bit counter can count to 63 a 7 bit counter to 127 and an 8 bit counter to 255 a 12 bit counter to 4095 and so on Frequency Counter Applications A binary counter can also be used as a frequency divider Take a look at the waveforms shown in Fig 3 Recall that aJK flip flop acts as a divide by 2 circuit As you can see in Fig 3 the output of the first flip flop has a period that is twice the period of the input pulses being counted That means that the output of the A flip flop has a frequency that is half that of the input pulse frequency Now look at the output of the B flip flop Again you can see that its frequency is half that of the A flip flop output A similar relationship exists in the remaining waveforms The output frequency of the B flip flop is one fo
287. torials should be used as a guide for wiring the yoke not for installing it The next problem is the small video board that fits on the back of the CRT It is shown in all illustrations as being horizontal Depending on the particular CRT supplied in your kit the board can be horizontal or angled at approximately 30 degrees If your video board is angled do not assume you ve HORIZONTAL DEFLECTION YOKE CRT FLYBACK TRANSFORMER Ta D LEM I ea STImSCIN EAS installed the CRT socket incorrectly and start hacking away at the board to remove the socket You probably have it correct because the socket s orientation cannot be changed without damaging the board or the socket If the board is angled when installed on the CRT leave it alone Final Adjustments The only user adjustments are the CRT focusing and the picture centering neither of which can be accurately done unless the monitor is being fed from a computer If you can run a short BASIC program that will fill the screen with large characters such as the H or Z and then make the focus and centering adjustments According to the manual the focus adjustment require that a small screwdriver be passed through a hole in the video board to the focus adjustment The hole is so small however that we could find no screwdriver that would pass through so the adjustment had to be made from the front of the video board which places your hand very close to the
288. ty systems For exam ple if you have a phone that s difficult to hear outside the house why not place a sound operated switch close to the phone and connect it to the Siren circuit with a horn speaker outside where you can hear it Such an arrangement doesn t require that a physical connection be made to the phone or wiring The hee haw Siren sound may not be everyone s cup of tea especially in ap plications like a remote telephone ringer t is easy to change the circuit to produce two other sounds for other applications Removing C or including a switch so it can be switched in and out of circuit stops the hee haw sound so the Siren gives a single tone You might also try connecting an electrolytic capacitor from pin 5 of IC2 to ground Depending on the value you choose say 10 1000 uF the Siren produces a variety of different sounds Or you can alter the speed of the Siren by increasing or decreasing the val ue of CI which has the affect of increas ing and decreasing the lengths of the hees and haws respectively W A complete kit of parts not including battery is available from Dick Smith Electronics P O Box 8021 Redwood City CA 94063 priced at 4 95 When ordering refer to catalog No DSFW2 K 2636 x i eS Litt BECAME RATHER OBVIOUS TO ME AFTER A FEW MONTHS that the problem with owning and operating a BSR Control Center System was to decide where to locate the command console
289. u can knock off almost 30 percent of the price dropping the cost to under 100 by building the monitor yourself Actually you won t be building the ZVM 122A but in stead Heathkit s HVM 122A see photos which is essen tially a clone kit version of the Zenith unit The price difference between the two monitors is primarily the cost of the factory assembly which can be done by you in two short evenings Why Monochrome At this point you re probably wondering why you should use a monochrome monitor when your home computer can generate color displays on a conventional TV set The answer to that is simple For most non color applications like word processing data files spreadsheets a sharper more legi ble and more convenient display is obtained from a con ventional wide band monochrome monitor like the Heath HVM 122A Because of inherent limitations caused by the 4 5 MHz bandwidth of our TV system about 40 characters per line is the most we can squeeze onto a TV screen before the display gets fuzzy Unfortunately modern business correspondences are usu ally 60 characters wide while spreadsheets and databases can be even more per line of sophisticated data So much professional software becomes either inconvenient or unusa ble when a TV set is used as the computer monitor On the other hand a professional quality monochrome monitor like Heath s HVM 122A has a bandwidth of 15 to 25 MHz which can easily resolve at least
290. uencies including 9 745 kHz and 15 155 kHz during the evening hours in North America You may enjoy Passport at 0100 GMT UTC an English show which focuses on South American features mu sic and news plus some religious items It is broadcast each weeknight Also with an English schedule is the government station in Buenos Aires Ar gentina RAE Radiodifusora Argentina al Exterior has English programs daily on 9 690 kHz and 11 710 khz from 0100 to 0200 and from 0400 to 0500 GMT UTC From Brazil the English programs from Radio Nacional Brasilia or Radt obras are it is reported an endangered species Brazilian government funding is at a bare minimum But as of this writing the schedule included programming at 0200 GMT UTC on 11 745 kHz and at Continued on page 104 e e M Adjustable Timer Continued from page 52 installed according to the layout obtained from the paper record or the breadboard and soldered in place on the pre etched board you end up with a neatly assembled printed circuit And the paper overlay can be filed away for future use should you decide to duplicate the circuit With the values shown for RI R2 and Cl the timer will have a range of from 0 to about 30 seconds The range can be either increased or decreased by changing the value of C1 The duty cycle may be altered by varying the value of R2 but that shouldn t be necessary under most conditions As
291. uilt several times from scratch and has never failed to operate the first time One word of caution though If the unit does not start timing immediately make sure that R1 is not set to the extreme low end of its range No other special precautions are needed Bi RESET Fig 2 The construction of the circuit is simplified by the use of a pre etched experimenter s board The layout is not critica and any arrangement convenient may be substituted EE Cu ccm 9861 g33 NVT e Cc Continued from page 102 1800 GMT UTC on 11 955 KHz There are plenty of privately owned Brazilian SW stations In fact Brazil is one of the most radio active countries in numbers of stations on shortwave Pro grams are of course in Portuguese Several stations to look for during the late afternoon and early evening hours are Radiodifussora Macapa 4 915 kHz Ra dio Inconfidencia 6 000 kHz Radio Ap arecida 6 010 kHz Radio Clube Paranaense 6 045 kHz Radio Universo 9 545 kHz Radio Guaiba 11 785 kHz ad id R Radio Electronics back issues 1985 3 00 Write in issues desired EN Radio Electronics back issues 1984 January 1984 not available Write in issues desired Radio Electronics back issues 1983 3 50 January February 1983 May 1983 not available Write in issues desired 3 50 Radio Electronics back issues 1982 4 00 Write in issues desired 7 Radio Electronics back issue
292. und in the speaker The next step is to find a suitable enclosure for the amplifier The kit s printed circuit has been made to slot sideways into a Zippy box as shown in Fig 3 There is enough room in the box for the speaker and bat tery too We have shown the amplifier with a standard potentiometer instead of the trimmer supplied with the kit the standard unit is convenient if the circuit 1s to be mounted in a box We have included an audio input socket and a power switch to allow for easy on off operation once the circuit is placed in an enclosure If you wish to run your amplifier from a plug pack adaptor a socket can be wired in parallel with the battery as indicated by the dashed line in Fig 3 If everything works as it should it is time to put the Amplifier to use Applications One rather usetul application of the Amplifier circuit s in an electronic mega phone It will be necessary to remove the 8 ohm loudspeaker from the output of the amplifier and instead fit it to the input Connect a horn speaker Dick Smith Cat C 2705 or similar to the output termi nals and speak into the original speaker which is now functioning as a micro phone Your voice will be amplified just as in a megaphone It s as simple as that Another use for the circuit is to hook it up to a pocket transistor radio A speaker i much more convenient than an ear phone Refer to Fig 4 Start by removing the wires to the earphone socket fr
293. urance lo addresses in the U S A Canada and Mexico when Check on money order accOmpames order Digi Key only ships orders within the continental U S Howse Canada end Menco WHEN ORDERING BY PHONE CALL 18003444539 AK call 218 681 6674 BY MAIL SEND YOUR ORDER TO DIGI KEY P O Box 677 Thiet Aiver Fails MN 56701 You may pay by check money order Master Charge VISA or C O D DIGI KEY GUARANTEE Any pans ox products purchased fiom Digi Key that prove to be defective wit be replaced or refund f rerumed within 90 days ftom recepi with a copy of your invoice PRICES SUBJECT TO CHANGE WITHOUT NOTICE CHARGES VOLUME DISCOUNT Add 82 00 0 00 99 99 os cea al Add 0 75 100 00 249 99 les3 10 Add 0 50 LE Less 15 Add 0 25 Less 20 No Charge MU TY HANDS ON ELECTRONICS ceo NO The Heathkit HVM 122A 12 inch amber monochrome video monitor provides excellent character definition for 40 or 80 characters per line at a fraction of the cost of comparable units By Herb Friedman L IF YOU ARE PRESENTLY USING ONE OF THE HOME AND family computers there s a good chance that you ll get more enjoyment and performance from the computer if you switch to a conventional wide bandwidth monochrome monitor such as the top rated amber screen Zenith ZVM 122A Un fortunately the over 100 price of the ZVM 122A might make it difficult to squeeze the Zenith monitor into a tight computer equipment budget But yo
294. urth that of the input The outputs of the C and D flip flops are sth and Vieth of the input frequency respectively The frequency division factor of a binary counter is simply 2 With four flip flops the frequency division factor is 16 A binary counter with eight flip flops will divide an input frequency by 25 2X 2X 2x 2X 2x 2X 2 x 2 256 If a 6 4 MHz input signal is applied to the 4 bit binary counter the output of the D flip flop will be 6 4 16 4 MHz or 400 kHz Preset Counters The term preset means to put a flip flop into one state or the other prior to another operation taking place Presetting a counter simply means loading a binary number into the counter prior to the input pulses being applied In many applications the preset can simply be a clear or reset opera tion If that were not done the binary numbers stored in the counter would have no meaning unless you knew the binary PRESET INPUT LOAO Fig 4 Flip flop pre set circuitry number stored in the counter previously Then you would have to subtract that number from the count to determine the number of input pulses that occurred It is not too hard to see that it s a lot simpler to clear the counter first so that the binary number stored in the counter exactly represents the number of input pulses that occurred On the other hand there are other applications where it is desirable to begin counting at some predetermined number For those applicati
295. ve a loudspeaker While at that point the signal level is of 9861 834d NV o go ANTENNA 2 x 10MEG IN SERIES d 28 E t _ c o Ti 9 VOLT 1K 8 ATTERY 80 SPEAKER Fig 1 The signal picked up by the antenna is fed across a tuned circuit which attenuates unwanted frequencies to three series connected amplifier stages to provide sufficient drive current for the speakers sufficient magnitude to drive a speaker that would not make the IC very happy It wants to work into a load with a reason ably high impedance resistance So the output of ICI c is fed through a 1000 ohm to 8 ohm matching transformer T1 to the speaker Putting it Together Using Fig 2 as a guide begin assem bling the circuit Place and solder the resistors and capacitors first taking extra care that C4 CIO and Cll are properly oriented Note To obtain R4 and R6 the two 20 megohm resistors wire two lO megohm resistors in series There is room allowed for two resistors in those posi tions on the printed circuit board Make sure that all the components are posi tioned neatly and are properly dressed be fore soldering them in Connect the 470 000 ohm trimmer potentiometer RV to the circuit in the position shown Note that Fig 2 shows a 500 000 ohm chassis mounted potentiometer in that position to allow the circuit to be tuned once placed inside a project box Next solder in the variable
296. video systems as well as microprocessors and computers The book s initial chapter explains basic semiconductor theory how semiconductor devices operate and what thev do in a circuit giving the beginning reader a solid foundation for the more complicated concepts and applications that follow Each chapter contains a summary followed by a short quiz to reinforce the information presented The authors of Basic Electronics Technology combined their many years of teaching experience and hands on knowledge to present an easy to understand guide to basic electronics theory application and troubleshooting Basic Electronics Technology will be available through bookstores and college stores at a suggested retail price of 19 95 Linear IC Equivalents And Pin Connections By Adrian Michaels Linear C Equivalents and Pin Connections Book No 141 based on Continued on page 15 Eye t ee re 4 ul My da E sng e High Tech How To e Robotics Ste e Space Age Projects Computers e Digital Electronics e Telecommunications e And much more e Artificial Intelligence Select 9 Books for Only Values to 107 75 ane DESIGNING amp BUDE E ELECTRO INC GAUSETS WITS PROJECTS noe A ccecTAonics Book D ug eep In Step With the Future a Part of the Fascinating World of Technology 2 75 HW TO BESIBN BUILE n j TROUBLES HOT IN OMICROPROUCES SQ
297. w it Works At the heart of the Power Supply Balance Indicator there are two comparator pairs from an LM339N quad comparator One set of comparators drives the yellow positive and negative indicators the other pair jointly drives the red WARN LED3 The circuit shown in Fig 1 draws its power from the unregulated portion of the power supply which is regulated into a 30 volt supply for the circuit by Ul and U2 a positive and negative regulator pair Although the LM339N sees 30 volts the supply is actually 15 volts since it straddles the power supply ground One input of each com parator is also tied to ground The four comparators get their switching inputs from two parallel resistor divider strings Both strings have their ends tied between the power supplv s positive and negative output terminals The first string consisting of R4 R5 and R6 Q V P OUT 100K 1 R5 2 2K R7 100K 1 R6 100K 1 R8 50K R9 1 4 LM339 100K 1 o Vour E QUT DES Lr IN 7815T LM339N OUT SCE rink GND 7915T Fig 2 The pinouts of the integrated circuit and the two three terminal regulators used in the Indicator Those units in TO 220 packages are rated for currents up to 1 ampere divides the input voltage in half with output taps at 0 5 The other string made up of R7 R8 and R9 also divides the input voltage in half with taps at 10 The 0 5 R4 R5 R6 string drives the two comparators control
298. ween the batteries are connected in series giving a 4 5 volt supply It is im Circular version of flasher PCB assembled with one or two LEDs Insulation tape to prevent short circuiting Screw glued onto PCB Circular PCB with pattern cut out as shown copper side down Circle of cardboard or blank PCB material to hold batteries in position 3 silver oxide watch batteries two with positive side up one with negative side up Matching nut glued to blank area in centre of PCB Circular PCB same as above with copper side up portant that the slots are oriented correctly to each other if you had X ray eyes and could look through the assembly the slots would form a Y pattern If the printed circuit boards are as sembled and the battery polarities ori ented as shown you shouldn t have any problems The supply assembly can be glued to the back of the flasher board or it can be held on by the wire connecting the positive supply to the flasher The supply is turned on and off by screwing and un screwing the rearmost PC board so that contact is made or broken with the bat teries This is just one idea of course there are many other ways to go For other ideas why not have a look at some elec tronic brooches in a modern jewelry shop See how their brooches are made and copy them ELECTRONIC DICE Imagine an electronic die that not only rolls and displays the result but turns of
299. ween the voltage and current of RF energy travelling up the line That relationship is exactly the same as would have occurred across and through a pure resistor having the same value say 50 ohms as the characteristic impedance of the cable It may help to grasp this concept if one is to visualize a very short burst of RF energy transmitted up the line so short that 205 C Fig 1 Three basic antennas for which the feed point impedances are known with reasonable accuracy The quarter wave dipole A has an approximate impedance of 72 ohms the quarter wave folded dipole B approximately 288 ohms and the quarter wave ground plane antenna C a bit less than 20 ohms If you differ on the last impedance refer to the text its trailing edge has left the transmitter long before its leading edge has reached the load at the far end Thus something in the manner of a fired projectile or even a thrown tennis ball it is in a kind of limbo while influenced initially by the manner of its launch its subsequent movement is largely a factor of its environment And it knows nothing about what lies in store for it at the end of its journey We can carry the analogy a little further If the tennis ball ultimately hits a brick wall it will bounce off or be reflected simply because the brick wall represents a gross mismatch to the manner in which energy is stored in the moving ball A softer object such as a bale of hay may well have abs
300. will be evident the output at pin 3 will remain low when the circuit is in the reset state Upon pressing the START button SI the output will go high and remain at that level until it has timed out then it will once more return to a low That low to high transition or pulse may be used as a keying signal for operation of some peripheral circuit or equipment The capacitors designated as C2 and C3 are somewhat optional However they are recommended for best overall operation Stray signal pickup may be introduced into pin 5 if it is left unbypassed If C3 is omitted and the power supply bus 1s not too stable the pulses from the timer may find their way back onto the common supply lines and into other circuits being supplied by that potential The values of C2 and C3 are not critical however for C2 the manufacturer recommends a 0 0l uF unit but for C3 almost any small electrolytic available to you that s in the range indicated in Fig 1 should do just fine Boxing Time If you intend after experimenting with the circuit to build the Adjustable Timer into a permanent adjunct to your test GA SEU NONIS MO Me ocere tf aei nm 9H PNIS Hee Da Pu s P pe SIS pae fett na P bench it is suggested that it be placed into a suitable en ritos Ange Qe Tei e ns ra Nina P PS Ardea e I Phi Mert ftrt re START closure There is very little reason to use a metal case unless of course you just happen to have one handy otherwise
301. xa pleasure to use Of cou sa the winners smile and the losers stif say hurry ug and deal tut the Digtel Cribbage Board verifies to both pkyers that eaeh entry is correct Since the scorekeeper s com posed of twa identical crcuits to accommodate two players only Ore circuit is shown 3cshe matically in Fig 1 However kesp in mind that two suc cir cits are needed and are ar ranged sid2 by side te opposite directions on the printec circuit foil pat esr Wren the board is placed between two o pesing players each dayar has one hel turn pa3e GRRL H44 NVI Photo by Water Herstatt t LP HANDS ON ELECTRONICS N A of the board facing him while he is still able to view his opponent s score on the other half Each circuit is composed of two separate counters with the score count being fed into both One counter a two digit unit capable of counting to ninety nine registers play points That counter which resets to zero before entering each new play displays the last play count entered The other a three digit counter counts to one hundred and ninety nine and is reset only at the start of a new game The second counter shows total points for all points entered during the game With low cost in mind the circuit was constructed of all CMOS integrated circuits IC s Inexpensive computer type keyboard switches were used for the COUNT PLAY CLEAR and game RESET controls The controls an
302. xas has a gripe Seeking to obtain several needed scanner frequencies he reports that he went to the local outlet of an electronics chain store and picked up a frequency directory promising all manner of frequencies in cluding railroad and aircraft listed Sez Leo when he got it home he realized that the book was a sheep in wolf s clothing having only very sparse and spotty coverage in all areas rather than the in depth coverage implied The two frequencies he wanted most were those of the Texas State Railroad Commission and also NASA s aero nautical operations in El Paso Leo wrote if you ve already disposed of it then keep Continued on page I8 SINGLE DEALER UNIT 10 UNIT PRICE PRICE RCA 36 CHANNEL CONVERTER CH 3 OUTPUT ONLY 2995 18 00 ea PIONEER WIRELESS CONVERTER OUR BEST BUY 8895 72 00 ea LCC 58 WIRELESS CONVERTER 9295 7600 ea JERROLD 450 WIRELESS CONVERTER CH 3 OUTPUT ONLY 105 95 90 00 ea SB ADD ON UNIT 109 95 58 00 ea BRAND NEW TRIMODE UNIT FOR JERROLDS Call for specifics MINICODE N 12 109 95 58 00 E MINICODE N 12 VARISYNC 11995 6200 ea MINICODE VARISYNC W AUTO ON OFF 17995 11500 ea M 35 B CH 3 OUTPUT ONLY 18995 70 00 ea M 35 B W AUTO ON OFF CALL FOR AVAILABILITY 199 95 125 00 ea MLD 1200 3 CALL IF CH 2 OUTPUT 10995 58 00 ea INTERFERENCE FILTERS CH 3 2495 1400 ea JERROLD 400 OR 450 REM
303. zontal frequencies are identical In B the horizontal frequency is twice the vertical In C the vertical frequency is twice the horizontal In D the vertical frequency is three times the horizontal In E the pattern shows a three vertical to two horizontal ratio In all cases the horizontal and vertical signals have the same phase and amplitude 986 add NVvf C2 HANDS ON ELECTRONICS wo gt TELEPHONE LINE TESTER Getting telephone service restored is a Snap when you know who to call this simple tester points you in the right direction By Herb Friedman L wirH ONE BOLD STROKE OF A PEN OUR GOVERNMENT broke up Ma Bell and created a multitude of problems for the consumer Unfortunately one of the disastrous effects of that so called victory is that responsibility for repair of tele phone equipment has been foisted on the subscriber Now your local telephone company handles only repairs to the line itself while whats left of Ma Bell takes care of the instru ment itself provided that you rent your equipment from them If you don t rent from them it s tough luck fella Essentially you end up playing Russian Roulette when your phone doesn t work If you call in the wrong outfit you can be stuck for a service charge of about 50 or more and still not get your service restored because as they say It s not nry job The problem has become so bad that there s been a ru

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